JPH043859A - Method of controlling number of operating device of small-sized absorbing type cold and hot water heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the number of small absorption type water chiller/heaters in operation.

[Conventional technology]

The conventional method for controlling the number of operating small absorption chillers uses a step thermostat to determine the number of operating chiller/hot water machines based on the current chilled/hot water temperature. This type of control method was developed in Japanese Patent Application Laid-open No. 59
A technique described in Japanese Patent No. 49465 is known.

[Problem to be solved by the invention]

In the above conventional technology, as shown in Fig. 3, the number of operating refrigerators is determined by the temperature of hot and cold water, and when the load is large, cooling to 10 degrees Celsius is performed in combination operation, and the number of refrigerators is set to 1.
If the cooling becomes insufficient, the temperature of the chilled water will rise, and the system will go into batch operation again, resulting in the possibility that the temperature of the chilled water will not cool down to below 10°C, resulting in the problem of not being able to fully utilize its cooling capacity.

In addition, small absorption type water chillers/heaters do not have a capacity control function, and in order to control the temperature of chilled/hot water, the operation of the chiller/heater must be
0N-OFF control by stopping is the only method, and furthermore,
The small absorption type water chiller/heater has its own thermistor, and when the chilled water temperature falls below 7°C, it detects proper cooling and automatically shuts down, causing a problem in which the unit deviates from unit control operation.

Furthermore, in small absorption type water chiller/heaters, there is a time delay after receiving an operation command and starting operation until the cooling capacity reaches 100%, and after receiving a stop command and entering the stop operation, the cooling capacity decreases. Since there is a time delay before the load disappears, there is a problem that when the load is light, after receiving the stop command, the number of units may be deviated from the control due to overcooling.

An object of the present invention is to control the chilled water temperature at a target value regardless of the magnitude of the load, and to prevent automatic shutdown due to overcooling.

[Means to solve the problem]

In order to solve the problem of automatic start and stop due to overcooling, the temperature of the cold and hot water collecting section is detected with a thermistor, and a microcontroller (hereinafter referred to as MCU) calculates the temperature gradient from the temperature every minute. Predict the next cold and hot water temperature,
Based on this, the number of vehicles in operation is determined.

In addition, in order to solve the problem that cooling capacity cannot be achieved when the load is large, a target temperature is set, and the number of operating units is determined based on the deviation from the target temperature.

[Effect]

The unit control panel detects the temperature of the cold and hot water collection section using a thermistor. Based on this detected temperature, the deviation and slope from the target temperature are calculated by the MCU of the unit control panel. Based on this deviation, it is decided whether to increase or decrease the number of operating vehicles. Furthermore, based on the current temperature and gradient, the temperature of cold and hot water will be predicted ten minutes later, and the number of operating units will be increased or decreased. Thereby, the cold water temperature can reach the target temperature without reaching the appropriate cooling temperature.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The number control panel 1 uses a thermistor 3 that measures the temperature of the cold and hot water collecting section to take in the temperature of cold and hot water, and converts it into analog and digital data by the MCU mounted on the number control panel 1. Further, the number control panel 1 transmits operation and stop commands to the small-sized cold/hot water machines 21 to 24 via communication lines 51 to 54.

Furthermore, the small-sized cold/hot water machines 21 to 24 have thermistors 41 to 42 on their sides, and if they detect overcooling, they automatically stop themselves.

In the number control panel 1, the MCU determines (deviation) = (
The following calculations are performed: target temperature) - (current temperature) and (slope) = (current temperature) - (temperature one minute ago).

Furthermore, the calculation (expected temperature after 10 minutes)=(current temperature)+(slope)XIO is also performed.

Based on these calculation results, the following control law is used during cooling operation.

When the deviation is smaller than 11° C. and the slope is positive, that is, when the current temperature is 1° C. higher than the target temperature and the temperature is on the rise, the number control panel 1 increases the number of operating cold/hot water machines by one.

Furthermore, when the deviation is greater than 1°C and the slope is negative, that is, when the current temperature is 1°C lower than the target temperature and the temperature is on a downward trend, the number control panel 1 controls the number of operating chiller/hot water machines to be uniform. Decrease the number of units.

A small absorption type water chiller/heater has a cooling capacity of 100% from the start of operation.
There is a time delay until the cooling capacity reaches its full potential, and even after the operation is stopped, there is a time delay until the cooling capacity is no longer available.

For this reason, the control law is such that the next change in the number of vehicles is not made for 15 minutes after the change in the number of vehicles.

Additionally, in order to prevent automatic shutdown due to overcooling, the number of operating units is reduced by one when the predicted temperature after 10 minutes falls below the appropriate cooling prevention predicted temperature. This predictive control ignores the restrictions after the number of vehicles changes and reduces the number of vehicles.

Similarly, the control law for heating operation is such that when the deviation is greater than 1°C and the slope is negative, that is, the current temperature is 1°C lower than the target value.
℃ is low and the temperature is on a downward trend, the number control panel 1 will
Increase the number of operating vehicles by one.

Also, when the deviation is less than 11°C and the slope is positive,
That is, when the current temperature is 1° C. higher than the target value and the temperature is on the rise, the number control panel 1 reduces the number of operating devices by one.

During heating operation, there is a time delay from the start of operation until 100% heating capacity is achieved, so the number of units will not be increased or decreased for 15 minutes after the number of units is changed. However, even though the heating capacity is lost after the heating operation is stopped, there is no delay in time, so control is not performed based on the predicted temperature 10 minutes later during the cooling operation.

〔Effect of the invention〕

According to the present invention, since control is performed based on the deviation from the target temperature, when the load is large, the cold and hot water temperature can be controlled to be close to the target value.

In addition, since the temperature is controlled based on the predicted temperature after 10 minutes, the cold/hot water machines automatically stop due to proper cooling, thereby preventing deviation from the number control.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of an embodiment of the present invention.
FIG. 3 is a graph showing the control temperature of chilled water temperature, and is a graph for determining the number of units using a conventional step thermostat. 1...Number control panel, 21-24...Small absorption chiller/heater, 3,41-44...Thermistor, 51-54.
・・S1～C；4- Value profit

Claims (1)

[Claims] 1. In a multi-unit control device equipped with a thermistor that detects the temperature of a collection part of cold and hot water, a communication function with a small absorption type water cooler and hot water machine, and a microcontroller, depending on the temperature gradient of the cold and hot water, 1. A method for controlling the number of small-sized absorption type cold/hot water machines in operation, comprising predicting the temperature of cold/hot water several minutes later and determining the number of small-sized absorption type cold/hot water machines in operation.