Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M13/00—Testing of machine parts
  • G01M13/003—Machine valves

Definitions

• the present disclosure relates to a method for monitoring a check valve condition in a modular fluid-fluid heat transfer arrangement which comprises a plurality of heat pump modules and, for each of the heat pump module, a check valve.
• the present disclosure further relates to a modular fluid-fluid heat transfer arrangement.
• Cold thermal grids are an evolution of district heating and district cooling systems, where combined district heating and district cooling system with aid of using heat pumps for heating and cooling can provide both cooling, heating and tap water preparation to buildings.
• the heat pumps used need to be smaller, less costly, easier to control and with lower technical complexity, e.g., with fewer and/or less complex sensors for measuring the space heat and tap water energy consumption than presently used heat pumps.
• the conventional heating and/or cooling systems are associated with several drawbacks. There is thus a need in the art for an improvement in this area.
• Another object of the disclosure is to provide a time-efficient monitoring method for a heat transfer arrangement.
• Another object of the disclosure is to provide a time-efficient but also cost-efficient fault monitoring method for a heat transfer arrangement.
• Another object of the disclosure is to provide an accurate monitoring method for a heat transfer arrangement.
• a method for monitoring a check valve condition in a modular fluid-fluid heat transfer arrangement which comprises a plurality of heat pump modules, each of the plurality of heat pump modules being fluidly connected to a first fluid grid via a respective first fluid flow path and to a second fluid grid via a respective second fluid flow path
• the modular fluid-fluid heat transfer arrangement further comprises, for each of the plurality of heat pump modules, a check valve arranged in a fluid flow path selected from the respective first fluid flow path and the respective second fluid flow path of the heat pump module, the check valve being configured to selectively close the fluid flow path
• the method comprising: for at least one of the plurality of heat pump modules:
• the first fluid grid may be a cold fluid grid or a hot fluid grid.
• the second grid may be a cold fluid grid or a hot fluid grid.
• the first fluid grid and the second fluid grid may be different fluid grids, i.e. , one may be the cold fluid grid and the other may be the hot fluid grid.
• module modular fluid-fluid heat transfer arrangement
• heat transfer arrangement or “arrangement”.
• modulear fluid-fluid heat transfer arrangement is here meant an arrangement which comprises a plurality of heat pump modules which are separate from and independently of each other.
• the plurality of heat pump modules may be introduced in a housing or a zone, e.g., in a controlled space in which the plurality of heat pump modules is arranged, without the need of being attached, e.g., fastened, or mounted, to each other.
• the arrangement may be configured to cover, i.e., being able to heat and/or cool and/or provide tap water to, an area.
• the area may be the whole, or a part of, a building.
• the fluid-fluid heat transfer arrangement may be configured to provide cooling or heating or tap water to the building, or a part of the building. If the arrangement is configured to provide heat to the building, the purpose of the arrangement is to supply heat from a cold to a hot side. If the arrangement is configured to provide cooling to the building (i.e., to remove heat therefrom), the purpose of the arrangement is to remove heat from the cold side.
• the fluid-fluid heat transfer arrangement may be a fluid-fluid heat pump arrangement configured to provide heat to a hot side fluid for heating the same.
• the fluid-fluid heat transfer arrangement may be a fluid-fluid cool pump arrangement configured to remove heat from a cold side fluid for cooling the same.
• the fluid-fluid heat pump arrangement and the fluid-fluid cool pump arrangement is in principle the same, the only difference being what the end user is interested in to achieve heating or cooling.
• the disclosed check valve may be configured to hydraulically connect the associated heat pump module to the first or second fluid grid.
• the disclosed check valve may be configured to disconnect the associated heat pump module from the first or second fluid grid.
• the check valve may be configured to control a flow direction of the fluid in the fluid flow path (i.e. , the first or second fluid flow path) in which the check valve is arranged.
• the check valve is configured to selectively close the fluid flow path such that the flow of the fluid is closed. When the fluid flow path is closed, the associated heat pump module is disconnected from the fluid grid. If the check valve works as expected, there is no flow in the fluid flow path or in the associated heat pump module when the check valve has closed the fluid flow path.
• the check valve is advantageous as it allows for controlling the associated heat pump module in an easy and efficient way.
• the check valve is further advantageous as it allows for connecting the associated heat pump module to the grid in a controlled way.
• the check valve is yet further advantageous as it allows for disconnecting the associated heat pump module from the grid in a controlled way. This is especially advantageous in case some malfunction of components in the heat transfer arrangement occurs. If malfunctions in the heat transfer arrangement is identified, the modular heat pumps may have to be disconnected from the grid in order to identify where in the arrangement the problem is located.
• the check valve In order to being able to close the arrangement in a safe and reliable way, the check valve has to work as expected such that the associated heat pump module may be closed in a safe and reliable way.
• the check valve may be arranged in the first fluid flow path or in the second fluid flow path.
• the check valve may be arranged on either an inlet pipe or an outlet pipe of the respective first fluid flow path or the respective second fluid flow path.
• the arrangement comprises a plurality of heat pump modules
• the arrangement also comprises a plurality of check valves since the arrangement comprises a check valve for each of the heat pump modules.
• the check valves may be individually arranged, i.e. , one check valve may be arranged on the inlet pipe of the associated first fluid flow path and another check valve may be arranged on the outlet pipe of the associated first fluid flow path. This should only be seen as an example and other configurations may be possible as well.
• close valve signal is here meant a signal instructing the check valve to be closed.
• the check valve will be closed when the close valve signal is provided to the check valve. Thereby, the fluid flow path will be closed. It should thus be noted that the provision of the close valve signal does not mean that the check valve will be closed, only that instructions are conveyed to the check valve instructing the same to close.
• the determination of the data set may be provided.
• data set is here meant everything from a single data point pertaining to the fluid temperature at one location and time position, to a plurality of data points determined e.g., for multiple time positions for one location, for multiple locations for one time position, or for multiple time positions and multiple locations within the arrangement.
• reference data set is here meant everything from a reference data point pertaining to a single reference temperature at one location and time position, to a plurality of reference data points determined e.g., for multiple time positions for one location, multiple location for one time position, or for multiple time positions and multiple locations within the arrangement.
• the reference data set may be determined for each of the heat pump modules of the arrangement such that each heat pump module has an associated reference data set. If the heat pump modules are equal, i.e., have identical properties such as compressor capacity etc., the reference data set may be equal for each of the heat pump modules. If the heat pump modules are different, the reference data set may be different for different heat pump modules. Thus, two heat pump modules which are equal may typically react in a similar way if the associated check valve does not work as expected.
• the reference data set may be determined in different ways, as will be detailed later. It is understood that the reference data set, independent on which way it is determined, will describe the estimated and/or expected behavior of the data set for a situation where the check valve is operating as expected or for a situation where the check valve is not operating as expected. Thus, the reference data set will reflect an estimation of the temperature behavior of the heat pump module for one of the two situations: check valve is actually closed, and check valve is still open I was not able to close.
• the check valve When there are malfunctions of the check valve, i.e., when the check valve is not operating as expected, the check valve may not be able to disconnect the associated heat pump module from the grid in a controlled way. Instead, the associated heat pump module may be disconnected from the grid by turning off the heat pump module or the check valve may be able to partly disconnect the heat pump module from the grid.
• the term “disconnect” should be interpreted as inactivate, i.e., there may not be any thermal exchange between the fluids, but the heat pump module may still be connected to the grid. This is disadvantageous compared to having the check valve disconnecting the heat pump module from the grid because it is more time-consuming.
• the disconnection of the heat pump module from the grid without having the check valve is less efficient and accurate compared to the solution in which the check valves are included. The disconnection is also provided in a less controllable way.
• the comparison criterion may be defined in different ways, as will be detailed later. It is understood that the comparison criterion, independent on which way it is defined, will indicate if the check valve is operating as expected or not, i.e., if the alarm signal is transmitted or not.
• the method indicates the malfunctioning of the check valve, i.e. , the method indicates that the check valve is not operating as expected.
• the check valve is considered to be operating as expected, i.e., in a correct way.
• the disclosed method helps to monitor a check valve condition of the check valve provided in the heat transfer arrangement.
• the check valve condition is typically relating to if the check valve is working as expected or if there are malfunctions of the check valve.
• an alarm signal is transmitted indicating a malfunctioning of the check valve if the comparison criterion is fulfilled, it is possible to indicate if there is something wrong with the check valve in an easy and efficient way.
• the alarm signal may indicate for an operator or user that something may be wrong with the check valve.
• the alarm signal is preferably transmitted to a control unit of the arrangement or to a remote control unit, wherein both the control unit and the remote control unit are configured to indicate for an operator that something may be wrong with the check valve.
• the determination of the data set may require that some time has passed from the time at which the close valve signal is provided to the check valve before the data set will pertain to fluid temperatures that deviates from their expected values.
• this behavior occurs since the fluid, at the time of sending the close valve signal, has not yet had time to react to the conditional change, if any, introduced to the system by the sending of the close valve signal.
• the reaction is described by heat conduction to the surroundings for the case of a check valve is operating as expected, since the fluid, by the closure of the check valve, will be prevented from further heat exchange in the heat exchanger thereby, by heat conduction to the surroundings, over time converging towards the temperature which is outside of the fluid flow path.
• the data set may be determined also at said time position of sending the close valve signal but may for such embodiments have to be determined also at later time positions at which the fluid has had time to react to the conditional change.
• the monitoring of the check valve e.g., the steps of the first aspect, may take 1 to 10 minutes to perform, preferably 3 to 7 minutes. It should however be noted that the monitoring of the check valve, e.g., the steps of the first aspect, may take longer or short time to perform as well.
• time spent for fault detection of the arrangement is decreased compared to conventional solutions.
• the downtime of the arrangement if any, may be decreased as well and thereby, a more cost-efficient but also energy-efficient solution is provided.
• the comparison criterion may be fulfilled when a difference between the data set and the reference data set exceeds a threshold.
• the method indicates the malfunctioning of the check valve, i.e. , the method indicates that the check valve is not operating as expected.
• the check valve is considered to be operating as expected, i.e., the method indicates that the check valve is operating in a correct way, and there is no malfunctioning of the check valve.
• the threshold may be set according to the properties of the heat pump arrangement, the properties of temperature sensors, the properties of the check valves etc. and therefore the particular numbers are not relevant for the inventive concept as such. That said, for typical example embodiment of the inventions, the threshold value may be within the range 0.2 °C to 3 °C, or 0.5 °C to 2 °C or 0.5 °C to 1 °C.
• the data set pertaining to the fluid temperature of the fluid flow path may therefore follow the reference data set. If the data set is following the reference data set, the difference between the data set and the reference data set may fall below the threshold. In other words, when the check valve is working as expected, the fluid temperature is following the reference temperature.
• the data set pertaining to the fluid temperature of the fluid flow path may deviate from the reference data set.
• the difference between the data set and the reference data set may exceed the threshold.
• the at least one reference temperature may be at least one ambient temperature.
• the ambient temperature may be a temperature within the heat pump module, just outside the heat pump module or may be a temperature outside the arrangement.
• the ambient temperature may be representative of a temperature to which the heat conduction and possible also heat convection at the first or second fluid flow path will depend.
• the fluid temperature may converge towards the ambient temperature.
• the fluid temperature may preferably exponentially converge towards the ambient temperature. This may be referred to as the fluid temperature following Newton’s law of cooling.
• the ambient temperature may be determined and stored during a test period.
• the ambient temperature may be determined in parallel with determining the data set.
• the at least one reference temperature may be at least one temperature of the fluid flow path which is determined in response to a provision of a reference close valve signal to the check valve when said check valve is operating according to its specification.
• the reference temperature will converge towards the ambient temperature. This is in line with the discussion above, in which the fluid temperature converges towards the ambient temperature when the check valve is working as expected.
• reference close valve signal is here meant a signal instructing the check valve to be closed when the check valve is operating according to its specification.
• the term “according to its specification” is here meant that the check valve is operating as expected, i.e. , the check valve is operating according to the principles set up by the check valve manufacturer.
• the reference data set for these embodiments will pertain to at least one reference temperature which has been determined when the check valve is working as expected.
• the check valve is operating according to its specification, there are no malfunctions of the check valve and the check valve is able to control the heat pump module in a desired way. Thereby, as the reference data set has been determined when the check valve is operating according to its specification, the reference data set has been determined when the check valve is operating in a correct way.
• the alarm signal is transmitted.
• the reference data set may be determined and stored during a test period in which the check valve is operating according to its specification.
• the reference data set may be provided during one or more test periods.
• the reference data set may be updated at a periodical basis in order for the check valve monitoring to be as exact as possible.
• a further reference data set which could be used as input to the comparison criterion which is fulfilled when a difference between the data set and the reference data set exceeds a threshold is disclosed below.
• the at least one reference temperature may be determined based on at least one temperature of a fluid flow path of at least one adjacent heat pump module, wherein the at least one temperature of the at least one adjacent heat pump module is determined in response to a provision of a reference close valve signal to an associated check valve of said at least one adjacent heat pump module.
• the at least one reference temperature may be determined based on at least one fluid temperature of one adjacent heat pump module only.
• the at least one reference temperature may be the at least one fluid temperature of said one adjacent heat pump module.
• the at least one reference temperature may be determined based on at least one fluid temperature of two or more adjacent heat pump modules.
• the at least one reference temperature may be a function of the associated at least one fluid temperatures of said two or more adjacent heat pump modules.
• the function may be the arithmetic mean of the associated at least one fluid temperatures of said two or more adjacent heat pump modules.
• the comparison criterion may be different.
• the comparison criterion may be fulfilled when a difference between the data set and the reference data set falls below a threshold.
• the method indicates the malfunctioning of the check valve, i.e. , the method indicates that the check valve is not operating as expected.
• the check valve is considered to be operating as expected, i.e., the method indicates that the check valve is operating in a correct way.
• the at least one reference temperature may be determined based on at least one fluid temperature of a fluid flow path of at least one adjacent heat pump module.
• the fluid temperature may correlate with a fluid temperature of other heat pump modules of the plurality of heat pump modules provided in the arrangement, preferably adjacent heat pump modules. This is because if the check valve does not work as expected, fluid may flow through the check valve towards the heat pump module. The temperature of that fluid may therefore be similar to the temperature of fluids flowing through the other heat pump modules of the arrangement.
• the data set pertaining to the temperature of the fluid flow path may correlate with the fluid temperature of adjacent heat pump modules.
• the fluid temperature correlates with the fluid temperature of other, e.g., adjacent, heat pump modules.
• the check valve is working as expected the fluid temperature of the fluid flow path of the heat pump module should have bad a correlation with the fluid temperature of the fluid flow path of other heat pump modules.
• Each heat pump module of the plurality of heat pump modules may comprise a refrigerant circulation path which includes a first heat exchanger unit, a compressor, a second heat exchanger unit and an expander being connected to one another in a sequence, wherein the first fluid flow path may extend through the first heat exchanger unit and the second fluid flow path may extend through the second heat exchanger unit.
• the first heat exchanger unit, the compressor, the second heat exchanger unit and the expander may be referred to as components of the heat pump arrangement as discussed above.
• Each heat pump module may comprise different types of sensors configured to monitor or detect the heat pump module or the arrangement.
• Each heat pump module may comprise one or more pumps configured to ensure that fluid in the heat pump module is always available where needed. It should however be noted that the heat pump module may comprise other components as well.
• the method steps (a) to (d) may be performed in a sequence for each of the plurality of heat pump modules.
• the term “sequence” is here meant that one check valve of the arrangement is provided with the close valve signal at the time. Another check valve may be checked when the previous check valve has been checked. Thus, the check of the previous check valve may have to be completed before the check of the next check valve is provided.
• the operated heat pump modules may be ramped up, if possible, such that the arrangement has the same output as before although running with fewer heat pump modules during the monitoring check.
• each heat pump module When the arrangement is operating in the normal operation mode, each heat pump module may be in operation and the power for each heat pump module may be controlled according to predetermined control laws.
• the control laws may be configured to control the operation of the associated heat pump module to operate in a normal heat pump module operation mode such that the arrangement is operating in the normal operation mode.
• the normal operation mode may include a common heat pump module operation mode of operating all heat pump modules of the plurality of heat pump modules in a similar way.
• the common heat pump module operation mode may be defined by an input power, i.e. , compressor capacity, being common for all heat pump modules of the plurality of heat pump modules. This implies that every heat pump module is always operating at the same input power.
• the control law may further comprise individually controlling the operation of each heat pump module of the plurality of heat pump modules to allow operating each heat pump module at a respective heat pump module operation mode.
• the respective heat pump operation mode of each heat pump module may be based on a predetermined fraction of a maximum input power of that heat pump module, wherein the predetermined fraction is common for all heat pump modules.
• the predetermined fraction may be determined based on a required arrangement output power Pout for the arrangement and a total maximum input power of all heat pump modules in the heat transfer arrangement. If dividing the required arrangement output power evenly between the maximum input power of all heat pump modules, the predetermined fraction is achieved. As said above, for this example embodiment, the predetermined fraction is common for all heat pump modules. Thus, if the predetermined fraction is 50% of the maximum arrangement output power, each heat pump module should operate with 50% of the heat pump modules respective maximum input power. For example, if the maximum input power of one heat pump module is 3 kW and of another heat pump module is 6 kW, the one heat pump module should operate with 1 .5 kW and the other one with 3 kW.
• the respective heat pump module operation mode of each heat pump module may be based on a predetermined time sequence alternating between a first state, where the heat pump module is not in operation, and a second state, where the heat pump module is operated at a predetermined input power.
• the control laws may be configured to control the operation of the associated heat pump module, by operating a circulation pump of the associated heat pump module to operate the arrangement in a normal operation mode such that the heat pump module is operating in the common heat pump operation mode or in the respective heat pump module operation mode.
• Each heat pump module may comprise a circulation pump.
• the modular fluid-fluid heat transfer arrangement may further comprise, for each of the plurality of heat pump modules, one or more temperature sensors arranged to measure at least the fluid temperature of the fluid flow path.
• the data set may be determined by using the fluid temperature determined by the one or more temperature sensors. If the arrangement comprises more than one temperature sensor for each heat pump module, these temperature sensors may be configured to determine the same fluid temperature or different fluid temperatures of the fluid flow path. By determining the same fluid temperature by using different temperature sensors provides for an accurate measurement of the fluid temperature. By determining different fluid temperatures of the fluid flow path by using different temperature sensors provides for a greater knowledge of the heat pump module and the fluid temperature. By the term “different fluid temperatures” is here meant fluid temperatures provided at different locations in the heat pump module or at different time positions.
• the modular fluid-fluid heat transfer arrangement may further comprise, for each of the at least one heat pump module, two temperature sensors arranged to measure a fluid temperature of the first fluid flow path and a temperature of the second fluid flow path, respectively. This is advantageous as it allows for a better knowledge of the heat pump module and the arrangement.
• the temperature sensor allows obtaining data sets pertaining to the fluid temperature. This should be interpreted broadly to encompass any temperature sensor capable of providing temperature-based data.
• the temperature sensor may be in physical contact with the fluid, such as a thermometer, thermocouple, thermistor etc. However, the temperature sensor may alternatively be based on remote sensing, such as e.g., spectrally resolved IR imaging or the like. Irrespective of which technique is chosen, the data set will relate to the temperature of the fluid and thereby be useful to be compared to reference data in the method of the disclosure. It should be noted that other sensors capable of providing temperature-based data may be used as well.
• the modular fluid-fluid heat pump arrangement may further comprise a control unit configured to control an operation of each of the plurality of heat pump modules.
• control unit is here meant any device or unit configured to control an operation of the plurality of heat pump modules.
• the arrangement comprises one control unit which is configured to control the operation of each of the plurality of heat pump modules.
• each heat pump module may have a respective control unit which is configured to control the operation of the associated heat pump module.
• the control unit may be e.g., a microprocessor or a central processing unit, CPU.
• the control unit may be configured to control the power and enablement of the heat pump module operation.
• the control unit may be wired, or wireless connected to each of the heat pump modules.
• One or more of the method steps according to the first aspect may be performed by, or at least initiated by, the control unit. This is advantageous as it allows for the method steps to be performed in an efficient way in which one or more of the method steps are performed or initiated by the same unit. If all method steps are performed or initiated by the control unit, there is no need to transmit information between a lot of different units in the arrangement, but all information is obtained by the control unit.
• the control unit may be configured to obtain, for each heat pump module, the data set pertaining to the fluid temperature of the fluid flow path of the associated heat pump module.
• the control unit may also be configured to obtain the reference data set pertaining to the reference temperature.
• Each temperature sensor may be connected to the control unit thus allowing the control unit to obtain measured fluid temperature data.
• the method may be performed in response to that at least one heat pump module of the plurality of heat pump modules receiving a trigger signal or at a periodical basis.
• the trigger signal may be output from, or at least initiated by, the control unit.
• the trigger signal may be an output in response to an error event being detected in one of the heat pump modules.
• the trigger signal may be an output in response to a request from a remote server or the control unit which may trigger the monitoring check to be performed.
• the method according to the first aspect is performed at a periodical basis, this may be once an hour, once a day or once a week. Other periodical bases may be used as well.
• the method may further comprise operating the modular fluid-fluid heat pump arrangement in a fallback operation mode being different from a normal operation mode of the modular fluid-fluid heat pump arrangement.
• the arrangement When the arrangement is operating in the fallback operation mode, the arrangement is operating in an operation mode which is different from the normal operation mode.
• the control unit may be configured to operate all heat pump modules with a check valve that is working as expected and the one or more heat pump modules which has a check valve which is not working as expected may be closed.
• the fallback mode may be defined as controlling a circulation pump for all heat pump modules of the arrangement, including the heat pump module having a check valve which is not working as expected, such that all heat pump modules have the same flow.
• the method may comprise providing an open valve signal to the check valve.
• the check valve is considered to operate as expected. If the check valve operates as expected, the check valve may open the fluid flow path. This may be provided by, or at least initiated by, that the check valve receives the open valve signal. The open valve signal may instruct the check valve to open the fluid flow path and thereby the associated heat pump module.
• the modular fluid-fluid heat transfer arrangement may comprise, for each of the plurality of heat pump modules, two check valves arranged in the first fluid flow path and in the second fluid flow path, respectively.
• the data set may comprise a data set curvature including a time series pertaining to the fluid temperature of the fluid flow path over time.
• the data set curvature may comprise a plurality of data set points pertaining to the fluid temperature over time.
• the data set curvature may comprise a continuous data set pertaining to the fluid temperature over time.
• the term “over time” may refer to a plurality of seconds up to an hour.
• the term “over time” refer to a plurality of minutes such as 1 to 10 minutes. This is advantageous as it allows for a check valve monitoring which is easy and exact.
• the reference data set may comprise a reference data set curvature including a respective time series pertaining to the fluid temperature of the fluid flow path over time wherein said time series is obtained in response to a provision of a reference close valve signal to the check valve when the check valve is operating according to its specification.
• the reference data set curvature may comprise a plurality of reference data set points pertaining to the reference temperature over time.
• the reference data set curvature may comprise a continuous reference data set pertaining to the fluid temperature over time.
• over time is here meant during preferably a plurality of seconds but may also mean during a plurality of minutes. This is advantageous as it allows for a check valve monitoring which is easy and exact.
• the comparison step in the method according to the first aspect may be provided in an exact and efficient way.
• the data set curvature and the reference data set curvature are provided in a similar way such that the comparison step may be provided in an easy and accurate way.
• the reference data set may be defined by a reference data set vector for the time series output. If that is the case, the method may further comprise, prior to comparing the data set and the reference data set, generating a first data set vector for the time series output.
• the data set and the reference data set may be compared for the respective speeds and/or deviations of the change in time.
• a modular fluid-fluid heat transfer arrangement comprising: a plurality of heat pump modules, each of the plurality of heat pump modules being fluidly connected to a first fluid grid via a respective first fluid flow path and to a second fluid grid via a respective second fluid flow path; for each of the plurality of heat pump modules, a check valve arranged in a fluid flow path selected from the respective first fluid flow path and the respective second fluid flow path of that heat pump module, said check valve being configured to selectively close said fluid flow path, and a control unit which is configured to, for each of the plurality of heat pump modules: provide a close valve signal to the check valve; determine a data set pertaining to a fluid temperature of the fluid flow path; and compare the data set with a reference data set pertaining to at least one reference temperature; upon the comparison fulfilling a comparison criterion: transmit an alarm signal for indicating a malfunctioning of said check valve.
• the disclosure may also in short be said to relate to a method for monitoring a check valve condition in a modular fluid-fluid heat transfer arrangement which comprises a plurality of heat pump modules and, for each of the heat pump modules, a check valve arranged in a fluid flow path of the heat pump module and configured to selectively close the fluid flow path, the method comprising: providing a close valve signal to the check valve; determining a data set pertaining to a fluid temperature of the fluid flow path; comparing the data set with a reference data set pertaining to at least one reference temperature of the fluid flow path; and if a difference between the data set and the reference data set exceeds a threshold: transmitting an alarm signal for indicating a malfunctioning of said check valve.
• Figure 1 illustrates a modular fluid-fluid heat transfer arrangement
• Figure 2 is a flowchart illustrating a method for monitoring a check valve condition in a modular fluid-fluid heat transfer arrangement.
• a modular fluid-fluid heat transfer arrangement 100 is illustrated by way of example.
• the modular fluid-fluid heat transfer arrangement 100 is preferably for heating and/or cooling and/or providing tap water to buildings or the like.
• the modular fluid-fluid heat transfer arrangement 100 is also referred to as “heat transfer arrangement 100” or “arrangement 100”.
• the heat transfer arrangement 100 has a first side 161 and a second side 162.
• the heat transfer arrangement 100 comprises, at the first sidel 61 , a first fluid grid 111.
• the heat transfer arrangement 100 is connected, by the first side 161 , to a first fluid side 101 via the first fluid grid 111.
• the heat transfer arrangement 100 further comprises, at the second side 162, a second fluid grid 112.
• the heat transfer arrangement 100 is connected, at the second side 162, to a second fluid side 102 via the second fluid grid 112.
• the first fluid grid 111 may comprise first inlet and outlet junction pipes 113, 114.
• the second fluid grid 112 may comprise second inlet and outlet junction pipes 115,116.
• the first fluid side 101 may be a cold fluid side or a hot fluid side.
• the second fluid side 102 may be a cold fluid side or a hot fluid side.
• one fluid side of the first and second fluid side 101 , 102 is the cold fluid side and the other one of the first and second fluid sides 101 , 102 is the hot fluid side.
• the heat transfer arrangement 100 further comprises two heat pump modules 130a, 130b. It should be noted that the heat transfer arrangement 100 may comprise more than two heat pump modules.
• the respective heat pump module 130a, 130b is connected to the first fluid grid 111 via a respective first fluid flow path 121 .
• the respective heat pump module 130a, 130b is connected to the second fluid grid 112 via a respective second fluid flow path 122.
• the first and second fluid flow paths 121 , 122 are defined by a respective non-solid line.
• the fluid flow paths 121 , 122 which extends through the heat pump module 130a are illustrated with dotted lines.
• the fluid flow paths 121 , 122 which extends through the heat pump module 130b are illustrated with dashed lines. It should be noted that the fluid flow path 121 , 122 which extends through the heat pump module 130a are separated from the fluid flow paths 121 , 122 which extends through the heat pump module 130a, 130b.
• the first fluid grid 111 is configured to supply a first side fluid from the first fluid side 101 to the heat transfer arrangement 100.
• the first fluid grid 111 is further configured to return the first side fluid from the heat transfer arrangement 100 to the first fluid side 101. If the first fluid side 101 is a cold fluid side, and energy should be retrieved therefrom, the first side fluid may be colder when being returned to the first fluid side 101 than when being supplied from the first fluid side 101 .
• the second fluid grid 112 is configured to supply a second side fluid from the heat transfer arrangement 100 to the second fluid side 102.
• the second fluid grid 112 is further configured to return the second side fluid from the second fluid side 102 to the heat transfer arrangement 100. If the second fluid side 102 is the hot fluid side, and energy should be supplied thereto, the first side fluid may be colder when being returned to the second fluid side 102 than when being supplied to the second fluid side 102.
• the fluid-fluid heat transfer arrangement 100 may be a fluid-fluid heat pump arrangement configured to provide heat to the hot side fluid for heating the same.
• the fluid-fluid heat transfer arrangement 100 may be a fluid-fluid cool pump arrangement configured to remove heat from the cold side fluid for cooling the same.
• the first fluid side 101 may be an evolution of district heating and district cooling systems, where combined district heating and district cooling system with aid of using heat pumps for heating and cooling can provide both cooling, heating and tap water preparation to buildings.
• the first fluid side 101 may be coupled to a downhole heat exchanger, or borehole heat exchanger.
• the second fluid side 102 may be a heating system, such as radiators or tap water systems, in the building.
• the first fluid side 101 may be a cooling system in the building.
• the second fluid side 102 may be an evolution of district heating and district cooling systems, where combined district heating and district cooling system with aid of using heat pumps for heating and cooling can provide both cooling, heating and tap water preparation to buildings.
• the second fluid side 102 may be coupled to a downhole heat exchanger, or borehole heat exchanger.
• the heat transfer arrangement 100 comprises two heat pump modules 130a, 130b.
• Each heat pump module 130a, 130b comprises first inlet and outlet ports 131a, 131 b and second inlet and outlet ports 132b, 132a.
• the first inlet and outlet ports 131a, 131 b are connected to the first fluid grid 111.
• the first inlet and outlet ports 131a, 131b are connected to the first fluid grid 111 via the first inlet and outlet junction pipes 113, 114. respectively.
• the second inlet and outlet ports 132a, 132b are connected to the second fluid grid 112.
• the second inlet and outlet ports 132a, 132b are connected to the second fluid grid 112 via the second inlet and outlet junction pipes 115, 116 respectively.
• the two heat pump modules 130a, 130b are connected in parallel to each other. This is achieved by their respective first inlet and outlet ports 131a, 131 b which are connected to the first inlet and outlet junction pipes 113, 114 respectively, and by their respective second inlet and outlet ports 132a, 132b which are connected to the second inlet and outlet junction pipes 115, 116, respectively.
• Each heat pump module 130a, 130b further comprises a refrigerant recirculation loop 134.
• the refrigerant recirculation loop 134 comprises a first heat exchanger unit 135 and a second heat exchanger unit 137 as well as a compressor 136 and an expander 138.
• the first heat exchanger unit 135 is fluidly connected to the first inlet and outlet ports 131a, 131b.
• the first heat exchanger 135 is connected to the first inlet and outlet junction pipes 113, 114 via the first inlet and outlet ports 131a, 131 b, respectively.
• the second heat exchanger unit 137 is fluidly connected to the second inlet and outlet ports 132a, 132b.
• the second heat exchanger unit 137 is connected to the second inlet and outlet junction pipes 115, 116 via the second inlet and outlet ports 132a, 132b, respectively.
• the refrigerant circulation loop 134 preferably circulates a refrigerant through the first heat exchanger unit 135, the compressor 136, the second heat exchanger unit 137 and the expander 138. If the first fluid side 101 is the cold fluid side, the refrigerant and the first side fluid are configured to exchange thermal energy between each other in the first heat exchanger unit 135 such that a temperature of the refrigerant increases and a temperature of the first side fluid decreases. The first side fluid is circulated from the first heat exchanger 135 to the first fluid side 101 . The refrigerant is circulated from the first heat exchanger unit 135 to the compressor 136 which is configured to increase the temperature and pressure of the refrigerant even further before supplying the refrigerant to the second heat exchanger unit 137.
• the refrigerant and the second side fluid is configured to exchange thermal energy between each other in the second heat exchanger unit 137 such that a temperature of the refrigerant decreases and a temperature of the second side fluid increases.
• the second side fluid is circulated in from the second heat exchanger unit 137 to the second fluid side 102.
• the refrigerant is circulated from the second heat exchanger unit 137 to the expander 138 which is configured to control an amount of refrigerant released into the first heat exchanger unit 135.
• the arrangement 100 further comprises, for each of the heat pump modules 130a, 130b, a check valve 140a, 140b.
• the check valve 140a, 140b is arranged in a fluid flow path selected from the respective first fluid flow path 121 or the second fluid flow path 122 of the heat pump module 130a, 130b.
• the arrangement 100 comprises, for each of the heat pump modules 130a, 130b, two check valves 140a, 140b, wherein one check valve 140a is arranged in the first fluid flow path 121 and another check valve 140b is arranged in the second fluid flow path 122.
• one check valve 140a is arranged at the inlet junction pipe 113 of the first fluid flow path 121 and the other check valve 140b is arranged at the inlet junction pipe 115 of the second fluid flow path 122.
• one check valve 140a is arranged at the outlet junction pipe 114 of the first fluid flow path 121 and the other check valve 140b is arranged at the outlet junction pipe 116 of the second fluid flow path 122.
• check valves 140a, 140b may be arranged in other ways as well, i.e., one at the inlet junction pipe 113 of the first fluid flow path 121 and one at the outlet junction pipe 114 of the first fluid flow path 121 or one at the inlet junction pipe 113 of the first fluid flow path 121 and one at the outlet junction pipe 116 of the second fluid flow path 122.
• the check valve 140a, 140b is configured to selectively close the fluid flow path (i.e., the first or second fluid flow path 121 , 122).
• the arrangement 100 may comprise, for each heat pump module 130a, 130b, one check valve 140a, 140b arranged in either the first fluid flow path 121 or the second fluid flow path 122.
• the first fluid flow path 121 may extend through the first heat exchanger unit 135 and the second fluid path 122 may extend through the second heat exchanger unit 137.
• the arrangement 100 further comprises, for each heat pump module 130a, 130b, two temperature sensors 150. It should however be noted that the arrangement 100 may comprise, for each heat pump module 130a, 130b, one temperature sensor or more than two temperature sensors. Each temperature sensor 150 is configured to measure at least a fluid temperature of the fluid flow path (i.e., the first or second fluid flow path 121 , 122). As illustrated in figure 1 , the temperature sensor 150 may be arranged at different positions in the heat pump module 130a, 130b. Hence, the temperature sensor 150 may be arranged at the inlet junction pipes 113, 115 of the fluid flow paths 121 , 122 or at the outlet junction pipes 114, 116 of the fluid flow paths 121 , 122.
• the arrangement 100 may comprise further temperature sensors (not illustrated) arranged to determine the ambient temperature of the heat pump module 130a, 130b or the arrangement 100.
• the further temperature sensors may be arranged in the heat pump module 130a, 130b.
• the further temperature sensors may not be in contact with the fluid of the fluid flow paths 121 , 122.
• the arrangement 100 further comprises a control unit 133.
• the control unit 133 is configured to control an operation of each of the heat pump modules 130a, 130b.
• the control unit 133 may be wired, or wireless connected to the heat pump modules 130a, 130b.
• the temperature sensor 150 may be connected to the control unit 133, either wired or wirelessly.
• the further temperature sensors may be connected to the control unit 133, either wired or wirelessly.
• the control unit 133 may be configured to determine a data set pertaining to the fluid temperature of the fluid flow path 121 , 122.
• the data set may comprise a data set curvature including a time series pertaining to the fluid temperature of the fluid flow path over time.
• the control unit 133 may be configured to obtain a reference data set pertaining to a reference temperature.
• the reference temperature may for some example embodiments be the at least one ambient temperature of the heat pump module 130a, 130b or the arrangement 100.
• the reference temperature may for some example embodiments be at least one temperature of the fluid flow path 121 , 122.
• the reference temperature may for some example embodiments be at least one fluid temperature of a fluid flow path 121 , 122 of at least one adjacent heat pump module 130a, 130b.
• the reference data set may comprise a reference data set curvature including a respective time series pertaining to the fluid temperature of the fluid flow path over time wherein said time series is obtained in response to a provision of a reference close valve signal to the check valve when the check valve is operating according to its specification.
• the reference data set may be determined and stored during a test period. If the reference data set is determined and stored during the test period in which the check valve 140a, 140b is operating according to its specification, it implies that the reference data set is determined at a time where it is made sure that the check valve 140a, 140b is operating according to its specification. This may be tested by using further test equipment at that time such as flow meters and/or position sensors.
• the data set and the reference data set may be compared for the respective speeds and/or deviations of the change in time.
• FIG 2 a flowchart illustrating a method 200 for monitoring a check valve condition in a modular fluid-fluid heat transfer arrangement 100 is shown by way of example.
• the modular fluid-fluid heat transfer arrangement 100 corresponds to the arrangement 100 as introduced in connection with figure 1 .
• the method 200 comprises (a) providing a close valve signal to the check valve 140a, 140b. Thereafter, the method 200 comprising (b) determining a data set pertaining to the fluid temperature of the fluid flow path in response to a provision of the close valve signal to the check valve 140a, 140b. Thereafter, the method 200 comprises (c) comparing the data set with a reference data set. The reference data set pertaining to at least one reference temperature. In a step (d), upon the comparison fulfilling a comparison criterion, the method 200 further comprising transmitting S201 an alarm signal for indicating a malfunction of the check valve 140a, 140b.
• the reference data set may be determined in different ways, as will be detailed below. It is understood that the reference data set, independent on which way it is determined, will describe the estimated and/or expected behavior of the data set for a situation where the check valve is operating as expected or for a situation where the check valve is not operating as expected. Thus, the reference data set will reflect an estimation of the temperature behavior of the heat pump module for one of the two situations: check valve is actually closed, and check valve is still open I was not able to close.
• the comparison criterion may be determined in different ways.
• the comparison criterion may be fulfilled when a difference between the data set and the reference data set exceeds a threshold.
• the threshold may be set according to the properties of the heat transfer arrangement 100, the properties of the temperature sensors 150, the properties of the check valves 140a, 140b etc. and therefore the particular numbers are not relevant for the inventive concept as such. That said, for typical example embodiment of the inventions, the threshold value may be within the range 0.2 °C to 3 °C, or 0.5 °C to 2 °C or 0.5 °C to 1 °C.
• the reference temperature may be at least one ambient temperature. If that is the case, the reference data set may be determined in advance, i.e. , be predetermined, or at the same time as when performing the rest of the method steps.
• the at least one reference temperature is at least one temperature of the fluid flow path which is determined in response to a provision of a reference close valve signal to the check valve 140a, 140b when said check valve 140a, 140b is operating according to its specification.
• the at least one reference temperature may be determined in advance, i.e. be predetermined, for a particular heat pump module at an occasion where it could be made certain that the check valve operated according to its specification. This could for example be achieved by performing calibration measurements during system maintenance.
• the correct operation of the check valve could for example be verified by measuring the flow rate in the fluid flow path 121 , 122 by means of a flow meter.
• the at least one reference temperature may, after an optional processing thereof, be stored in the modular fluid-fluid heat transfer arrangement 100, or in any peripheral device being accessible from said arrangement 100. Thus, for example embodiments utilizing this way of determining the reference data set, the determination is not made when performing the method per se and has instead to be made earlier.
• the combined information from the plurality of heat pump modules may be used.
• This method differs from the above-described method in that the reference data set may be determined at the same time as when performing the rest of the method steps.
• the at least one reference temperature may be determined based on at least one fluid temperature of two or more adjacent heat pump modules.
• the at least one reference temperature may be a function of the associated at least one fluid temperatures of said two or more adjacent heat pump modules.
• the function may be the arithmetic mean of the associated at least one fluid temperatures of said two or more adjacent heat pump modules. It is conceivable that the arithmetic mean is taken for all temperature values of each associated at least one fluid temperature, thereby resulting in a scalar.
• the arithmetic mean is taken between groups of temperature values which are expected to have similar values.
• the adjacent heat pump modules are identically or at least similarly constructed, it is reasonable to expect that the temperature value from a temperature sensor of one of these adjacent heat pump modules will be close to a temperature value of another adjacent heat pump module at a specific point in time after the close valve signal was received by the check valve.
• Temperature values from such corresponding sensors may advantageously be averaged to provide a mean temperature on which the reference data set may be based.
• the comparison criterion will be fulfilled when the data set differs from the reference data set, which may occur when the temperature of the fluid flow path at which the tested check valve 140a, 140b is arranged deviates “enough” (as determined by the threshold) from the reference temperature, which could be e.g. the ambient temperature.
• the reference temperature which could be e.g. the ambient temperature.
• a fluid temperature which does not agree with the ambient temperature will indicate that the tested check valve 140a, 140b has not been closed in spite of the check valve 140a, 140b receiving instructions to do close.
• the comparison criterion may be different.
• the comparison criterion may be fulfilled when a difference between the data set and the reference data set falls below a threshold.
• a reference data set which could be used as input to this comparison criterion is that the reference temperature may be determined based on at least one fluid temperature of a fluid flow path of at least one adjacent heat pump module.
• the comparison criterion will for the present embodiment be fulfilled when the data set is equal to or at least close to the reference data set, which may occur when the temperature of the fluid flow path at which the tested check valve 140a, 140b is arranged does not deviate “enough” (as determined by the threshold) from the temperature(s) of the fluid flow path(s) of adjacent heat pump module(s) 130a, 130b.
• “enough” as determined by the threshold
• a similar fluid temperature will indicate that the tested check valve 140a, 140b has not been closed in spite of the check valve 140a, 140b receiving instructions to close.
• the method steps (a) to (d) may be performed in a sequence for each of the plurality of heat pump modules 130a, 130b.
• all check valves 140a, 140b are checked when monitoring the check valve condition.
• the method 200 may be performed in response to that at least one heat pump module 130a, 130b of the arrangement 100 receives a trigger signal.
• the trigger signal may be received from an operator or from the control unit 133.
• the method 200 may be performed at a periodical basis.
• the method 200 may further comprise operating S203 the modular fluid-fluid heat transfer arrangement 100 in a fallback operation mode.
• the fallback operation mode may be different from a normal operation mode of the arrangement 100.
• the fallback operation mode may e.g., be to operate the heat pump module at a lower power.
• the method 200 may further comprise providing S202 an open valve signal to the check valve 140a, 140b.
• the fluid in the first or second fluid grid 111 , 112 may continue to flow, resulting in a different fluid temperature time decay than for the reference data set where the temperature, as a result from the closed check valve 140a, 140b, will follow the fluid temperature time decay of water standing completely still, i.e. , a temperature time decay determined by heat conduction to the surroundings.
• a relatively inexpensive and straight-forward implementation of the method of the disclosure is to determine the data set based on input data from a single temperature sensor 150.
• the data set may thus include one or more temperature values of the temperature of the fluid at the position of that temperature sensor 150.
• the comparison step may be carried out by taking the difference between the data set and the reference data set thus resulting in one or more temperature differences.
• a further relatively inexpensive and straight-forward implementation of the method of the disclosure is to determine the data set based on input data from a single temperature sensor 150.
• the data set may thus include one or more temperature values of the temperature of the fluid at the position of that temperature sensor 150.
• the comparison step may be carried out by taking the difference between the data set and the reference data set thus resulting in one or more temperature differences. Temperature(s) of the data set and reference data set at a time period after the close valve signal was provided to the check valve 140a, 140b is typically chosen to be able to identify the difference in fluid temperature decay time.
• the data set may include a plurality of temperature values as function of time, i.e., a time- resolved temperature curve.
• the reference data set may therefore also include a plurality of temperature values as function of time predetermined at a time where the check valve 140a, 140b was operating according to its specification.
• the comparison step may include taking the difference between temperature values of the data set and temperature values of the reference data set at different time positions after the close valve signal was sent to the check valve 140a, 140b.
• the time-resolved curves may be compared by more sophisticated algorithms such as curve fitting analysis etc.

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• 2023
  • 2023-11-02 EP EP23886441.7A patent/EP4612471A1/de active Pending
  • 2023-11-02 WO PCT/SE2023/051105 patent/WO2024096799A1/en not_active Ceased

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