EP0881440A2 - Verdampferabtausteuerung für ein Luftwärmepumpenaggregat - Google Patents

Verdampferabtausteuerung für ein Luftwärmepumpenaggregat Download PDF

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Publication number
EP0881440A2
EP0881440A2 EP97119032A EP97119032A EP0881440A2 EP 0881440 A2 EP0881440 A2 EP 0881440A2 EP 97119032 A EP97119032 A EP 97119032A EP 97119032 A EP97119032 A EP 97119032A EP 0881440 A2 EP0881440 A2 EP 0881440A2
Authority
EP
European Patent Office
Prior art keywords
temperature
evaporator
defrosting
air
heat pump
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP97119032A
Other languages
English (en)
French (fr)
Other versions
EP0881440A3 (de
Inventor
Luigi Rosso
Roberto Trecate
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RC Group SpA
Original Assignee
Rc Condizionatori SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rc Condizionatori SpA filed Critical Rc Condizionatori SpA
Publication of EP0881440A2 publication Critical patent/EP0881440A2/de
Publication of EP0881440A3 publication Critical patent/EP0881440A3/de
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/002—Defroster control
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/19—Pressures
    • F25B2700/197—Pressures of the evaporator
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2106—Temperatures of fresh outdoor air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2117—Temperatures of an evaporator

Definitions

  • Heat pumps are machines that use a cooling or refrigeration cycle (reverse Carnot cycle) to produce heat at medium and high temperatures.
  • the refrigerating machines that follow this cycle use energy in an external mechanical form (work - L), and as a result produce a transfer of heat energy from a low-temperature heat source (TL) to a high-temperature heat source (TH).
  • COP Coefficient of Performance
  • COP EH / L wherein EH is the heat energy yielded to the high temperature heat source TH.
  • TH and TL are expressed in degrees Kelvin. This relationship indicates that the lower the difference in temperature between the two heat sources, the greater the COP of the heat pump, for a same temperature TH of the hot source.
  • It basically consists of a compressor CP, a high-temperature heat exchanger (Condenser C o on hot source S c ), a low-temperature heat exchanger (Evaporator E v on cold source S f ) and an expansion valve VE.
  • the real machine Compared with an ideal machine, in which the transformations at the condenser and evaporator take place at the same temperature as the sources, the real machine has a worse COP because (for reasons due to heat flow) it has to operate with greater temperature differences.
  • the primary objective is to reduce the difference between the first and second terms of expression a) by reducing the individual differences between the temperatures in expressions b) and c).
  • Every cooling machine therefore has its own operating values TL - TE and TC - TH, based on its design.
  • the cold source is external ambient air and the hot source is the hot water produced at the condenser or the air in the space to be heated.
  • Heat exchange at the evaporator takes place between the coolant fluid, which evaporates, and the external air, whose enthalpic content declines. This is described as variation in enthalpic content, because the air cooling phenomenon during transit in the evaporator depends on parameters such as temperature and relative humidity.
  • Air evaporators used in heat pumps consists of sets of finned pipes. Coolant fluid flows inside the pipes, and the external ambient air flows outside them. When the air meets the cold surfaces of the set of finned pipes it deposits part of its moisture content on them in the form of condensate. The higher the absolute humidity of air entering the set of pipes, the greater the amount of condensate deposited.
  • Figure 2 shows a psychrometric chart for air.
  • the cooling transformation shown as 1-2 in the psychrometric chart under the conditions prevailing at point 1 (start of cooling), the absolute humidity of the air is high, while at point 2 (end of cooling), the humidity content of air is lower; transformation 1-2 takes place with condensate depositing on the surface of the set of pipes.
  • cooling transformation 3-4 the humidity content of the air before cooling is low, and does not vary up to the output; transformation 3-4 therefore takes place without that the condensate deposits.
  • the refrigerant or coolant fluid in the set of finned pipes acquires negative temperature values, which reduce the temperature of the outer surface of the pipes and fins to values of 0°C and below.
  • the condensate freezes and accumulates on the fins in the form of compact ice or frost. Ice increases the heat resistance and worsens the heat exchange between air and coolant fluid; the difference TL - TE increases, and the COP of the heat pump worsens.
  • frost formation evaporation temperature TE falls, although external air temperature TL remains constant.
  • the ice deposited on the evaporating pipes must therefore be removed in order to keep the COP of the machine high.
  • Defrosting cycle In heat pump cooling machines, a function called the "defrosting cycle" is periodically activated to melt the ice or frost deposited on the finned pipes. Defrosting can be performed in various ways (by reversal of cycle, injection of hot gas or ventilation, with electrical resistors, etc.). During the defrosting cycle the machine is inactive in the sense that the production of high-temperature heat energy is completely or partly interrupted.
  • the defrosting cycle runs periodically after a preset time has elapsed.
  • the machine control system usually allows this time to be set.
  • the heat pumps can be suitably preset on the basis of the climatic conditions in which they are intended to operate.
  • this system fails to take account of the influence of the other three variables (meteorological, seasonal and environmental conditions) in the formation of ice or frost on the finned pipes. Account must be taken of the worst-case condition of all three variables, which means that the defrosting cycles will be more frequent than necessary in intermediate seasons or when meteorological conditions are favourable.
  • thermometric probe on the evaporating unit detects temperature conditions that can give rise to ice formation, and controls defrosting.
  • This system requires each individual machine to be calibrated and set. It can be used for mass-produced machines or in combination with other systems. It presents the drawback of assuming that a close relationship exists between output temperature and the presence of ice on the unit. However, when the air temperature is low but the humidity content of the air is also low, no ice will form on the unit, but the system will still order the machine to defrost.
  • a calibrated differential pressure switch triggers the defrosting cycle. Ice formation on the evaporating unit causes not only an increase in heat resistance, but also an increase in resistance to the air flow crossing the unit. This system presents the drawback of being influenced by wind; it is also difficult to apply to heat pumps with axial fans on the evaporating unit.
  • the purpose of this invention is to eliminate the drawbacks of the previous technique and ensure that defrosting only takes place as and when necessary.
  • the new method forming the subject of this invention uses two temperatures to control heat pump defrosting cycles in the optimum manner for any climatic, meteorological, seasonal or environmental situation.
  • One of the temperatures can be detected by pressure measurement.
  • TL - TE must always be maintained within minimum values.
  • the method of management and control of heat pumps in accordance with the invention involves continual measurement of external air temperature TL and pressure PE of the coolant gas in the evaporator.
  • vapour pressure PE and saturation temperature TE are in a univocal relationship during change of phase; as a result, evaporation temperature TE can be obtained from a pressure gauge reading.
  • TL - TE or introducing systematic detection
  • frost forms on the unit.
  • value TL - TE is the minimum value possible, namely ⁇ Ti. This value incorporates all the information relating to the climatic, meteorological, seasonal and environmental situation in which the machine operates.
  • the new method of management and control of the heat pumps provides for a first forced defrosting cycle.
  • mean value ⁇ Ti which takes place between the 4th and 5th minutes after defrosting, is detected and stored. Under these conditions ice has not yet formed, or at most the amount of ice is so modest as not to affect the behaviour of the machine.
  • TL - TE gradually increases aver initial value ⁇ Ti.
  • the new mean ⁇ Ti value found between the 4th and 5th minutes is again detected and stored.
  • the monitoring system continually updates the ⁇ Ti value in this way, and thus follows the behaviour of the machine in accordance with developments in the meteorological situation (rain, fog, wind), and the seasonal and environmental situation (day/night, sun/shade).
  • the COP of the heat pump is always maintained at the highest possible values, and the number of defrosting cycles is minimised.
  • the new method and equipment eliminate the drawbacks of conventional systems. The number of operating hours being equal, the annual heat energy output of a heat pump controlled by the new method is 20% higher than that of the same machine with the conventional type of defrosting system.
  • ⁇ Tincrement is usually 8°C but this figure can be modified; field tests demonstrate that whereas higher values have no adverse effect on the operation of the machine, values under 8°C can cause an unnecessary increase in the frequency of defrosting cycles.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Defrosting Systems (AREA)
  • Air Conditioning Control Device (AREA)
EP97119032A 1997-05-27 1997-10-31 Verdampferabtausteuerung für ein Luftwärmepumpenaggregat Withdrawn EP0881440A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI971244 1997-05-27
IT97MI001244A IT1292014B1 (it) 1997-05-27 1997-05-27 Controllo dello sbrinamento dell'evaporatore in un impianto a pompa di calore ad aria

Publications (2)

Publication Number Publication Date
EP0881440A2 true EP0881440A2 (de) 1998-12-02
EP0881440A3 EP0881440A3 (de) 1999-10-06

Family

ID=11377230

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97119032A Withdrawn EP0881440A3 (de) 1997-05-27 1997-10-31 Verdampferabtausteuerung für ein Luftwärmepumpenaggregat

Country Status (2)

Country Link
EP (1) EP0881440A3 (de)
IT (1) IT1292014B1 (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001022014A1 (en) * 1999-09-24 2001-03-29 Arçelik A.S. Defrost control
EP1134519A3 (de) * 2000-03-15 2002-04-10 Carrier Corporation Verfahren und Vorrichtung zur Abtausteuerung für umkehrbare Wärmepumpen
ES2226545A1 (es) * 2001-11-22 2005-03-16 Oscam S.P.A. Instalacion y procedimiento para cortar barras metalicas en porciones de longitud predeterminada y dispositivo para la ordenacion del deposito temporal de porciones de barras metalicas.
WO2006045143A1 (en) * 2004-10-26 2006-05-04 Quantum Energy Technologies Pty Limited Control system for heat pump water heaters
DE102005054104A1 (de) * 2005-11-12 2007-05-24 Stiebel Eltron Gmbh & Co. Kg Verfahren und Vorrichtung zum Regeln eines Abtauvorgangs eines Verdampfers einer Kältemaschine
ITMI20150564A1 (it) * 2015-04-20 2016-10-20 Lu Ve Spa Procedimento e dispositivo di sbrinatura, in particolare per apparecchi per la refrigerazione ed il condizionamento dell'aria
DK178891B1 (en) * 2012-10-08 2017-05-01 Dixell S R L Control system for refrigerated equipment and apparatus with advanced energy saving features

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3110042A1 (de) * 1981-03-16 1982-09-30 Gesellschaft für Wärmepumpen und Energierückgewinnungsanlagen mbH, 7311 Holzmaden Verfahren und anordnung zum abtauen von eis an einem luftkuehler einer waermepumpe oder kaeltemaschine
DE3227604A1 (de) * 1981-07-29 1983-02-24 Olsberg Gesellschaft für Produktion und Absatz mbH, 5790 Brilon Automatische abtauregelvorrichtung fuer waermepumpen-verdampfer
DE3229135A1 (de) * 1982-08-04 1984-02-09 Siemens AG, 1000 Berlin und 8000 München Verfahren zum betreiben einer luft-wasser-waermepumpe und anordnung zur durchfuehrung des verfahrens
FR2539859A1 (fr) * 1983-01-24 1984-07-27 Comp Generale Electricite Procede et dispositif de regulation de la mise en degivrage et de l'arret du degivrage d'un evaporateur de fluide frigorifique pour pompe a chaleur
US4563877A (en) * 1984-06-12 1986-01-14 Borg-Warner Corporation Control system and method for defrosting the outdoor coil of a heat pump
JPS61101736A (ja) * 1984-10-23 1986-05-20 Mitsubishi Heavy Ind Ltd 空気調和機の除霜制御装置
JPS60117042A (ja) * 1984-10-26 1985-06-24 Hitachi Ltd 冷暖房兼用空気調和機
US4573326A (en) * 1985-02-04 1986-03-04 American Standard Inc. Adaptive defrost control for heat pump system
EP0285690A1 (de) * 1987-04-08 1988-10-12 Viessmann Werke GmbH & Co. Verfahren und Vorrichtung zur temperaturabhängigen Bedarfsabtauung von Kühlanlagen
US5507154A (en) * 1994-07-01 1996-04-16 Ranco Incorporated Of Delaware Self-calibrating defrost controller

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001022014A1 (en) * 1999-09-24 2001-03-29 Arçelik A.S. Defrost control
EP1134519A3 (de) * 2000-03-15 2002-04-10 Carrier Corporation Verfahren und Vorrichtung zur Abtausteuerung für umkehrbare Wärmepumpen
KR100413160B1 (ko) * 2000-03-15 2003-12-31 캐리어 코포레이션 가역식 열 펌프의 성에제거 제어용 시스템 및 방법
CN100340829C (zh) * 2000-03-15 2007-10-03 开利公司 对可逆热泵除霜控制的方法和实施该方法的系统
ES2226545A1 (es) * 2001-11-22 2005-03-16 Oscam S.P.A. Instalacion y procedimiento para cortar barras metalicas en porciones de longitud predeterminada y dispositivo para la ordenacion del deposito temporal de porciones de barras metalicas.
ES2226545B2 (es) * 2001-11-22 2007-01-01 Oscam S.P.A. Instalacion y procedimiento para cortar barras metalicas en porciones de longitud predeterminada y dispositivo para la ordenacion del deposito temporal de porciones de barras metalicas.
WO2006045143A1 (en) * 2004-10-26 2006-05-04 Quantum Energy Technologies Pty Limited Control system for heat pump water heaters
DE102005054104A1 (de) * 2005-11-12 2007-05-24 Stiebel Eltron Gmbh & Co. Kg Verfahren und Vorrichtung zum Regeln eines Abtauvorgangs eines Verdampfers einer Kältemaschine
DK178891B1 (en) * 2012-10-08 2017-05-01 Dixell S R L Control system for refrigerated equipment and apparatus with advanced energy saving features
ITMI20150564A1 (it) * 2015-04-20 2016-10-20 Lu Ve Spa Procedimento e dispositivo di sbrinatura, in particolare per apparecchi per la refrigerazione ed il condizionamento dell'aria
EP3086060A1 (de) * 2015-04-20 2016-10-26 Lu-Ve S.P.A. Abtauverfahren und abtauvorrichtung für kältegerät oder klimaanlagenvorrichtung

Also Published As

Publication number Publication date
IT1292014B1 (it) 1999-01-25
ITMI971244A0 (de) 1997-05-27
ITMI971244A1 (it) 1998-11-27
EP0881440A3 (de) 1999-10-06

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