CN1448674A - Air-cooled heat pump air-conditioning frost-melting controlling method - Google Patents

Air-cooled heat pump air-conditioning frost-melting controlling method Download PDF

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Publication number
CN1448674A
CN1448674A CN 03116149 CN03116149A CN1448674A CN 1448674 A CN1448674 A CN 1448674A CN 03116149 CN03116149 CN 03116149 CN 03116149 A CN03116149 A CN 03116149A CN 1448674 A CN1448674 A CN 1448674A
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air
defrost
evaporator
wind speed
heat pump
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CN 03116149
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CN1206496C (en
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谷波
景步云
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Shanghai Jiaotong University
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Shanghai Jiaotong University
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  • Defrosting Systems (AREA)

Abstract

The defrosting control of wind cooled heat pump is realized via determining the exit wind speed of the evaporator. The relationship between the evaporation temperature and the exit wind speed of the evaporator is first obtained through simulation of the system; the evaporation temperature is then calculated based on the wind speed tested with the wind speed sensor installed in the exit of the evaporator, the evaporator surface temperature is obtained based on the relationship between the evaporator surface temperature and the evaporation temperature, and whether or not to defrost is determined based on the evaporator surface temperature; and finally whether or not to end defrosting is determined based on whether the exit wind speed of the evaporator reaches the threshold for normal operation. The defrosting control method is simple, practical and power saving.

Description

Air-cooled heat pump air-conditioning defrosting control method
Technical field
What the present invention relates to is air-cooled heat pump air-conditioning system defrosting control method, particularly a kind ofly controls defrost method constantly by measuring air-cooled heat pump air-conditioner outdoor unit evaporator outlet wind speed.Belong to Thermal Power Engineering and Refrigeration ﹠ Air-Conditioning technical field.
Background technology
With the outdoor air is the heat pump air conditioner of thermal source, and when the evaporator surface temperature was lower than 0 ℃, airborne moisture can condense into frost at evaporator surface.Frost layer covers evaporator surface, hindered contacting of coil pipe and fin and air, greatly reduces the heat transfer efficiency of heat exchanger.Along with the increase of frost thickness, duct cross-section is diminished, air quantity reduces, and heat transfer boundary condition is constantly abominable, and the evaporator surface temperature constantly reduces, thereby evaporating temperature is also constantly reduced, and heating capacity also constantly reduces.Even make the passage total blockage, heat pump can't be worked.Therefore air-cooled.When heat pump moves in the winter time, need periodically defrost, and defrost control is a wherein difficult link.
Defrost time started and concluding time are promptly determined in defrost control, become an emphasis of present heat pump air conditioner research.In the prior art, the control method that the automatic defrosting that Chen Rudong and Xu Dongsheng narrate and study in " research of refrigerating plant Defrost method " (" Tongji University's journal ", 1998 26 5 phases of volume, 566-569 page or leaf) literary composition begins and finishes mainly contains:
1) time control defrost.Rule of thumb determine defrost periods and duration,, connect defrosting device, the beginning defrost with a time controller; Defrost continues designated time intervals and cuts off defrosting device.This is a kind of general defrosting control method, but its limitation is arranged, and is higher than 0 ℃ at outdoor air dry-bulb temperature, when perhaps air humidity was very low, potential evaporation device surface did not have frosting, but Ding Shi connection defrosting device, waste energy, and influence indoor air comfort.
2) temperature difference control defrost.The temperature difference with working medium in air under the operating mode and the evaporimeter is constant substantially.After the evaporator surface frosting, the remarkable variation of conducting heat, the temperature difference between the two become big.Utilize this variation, survey air themperature and evaporating temperature respectively, send according to the temperature difference that defrost begins and termination signal with two temperature sensing elements.When making in this way, establishing a capital in advance of control system itself and temperature range is difficult, and be very sensitive to the variation of heat pump air conditioner load.The frequent connection defrosting device of meeting if the while outdoor fan is out of order up to shutdown, wastes energy.
3) minute-pressure difference control defrost.It is relevant with frosting thickness that pressure when air flows through evaporimeter falls, and the frost layer is thick more, and pressure falls big more.Like this, the pressure differential of available minute-pressure difference controller induction evaporation mode device import and export is sent the defrost commencing signal.This minute-pressure difference controller price is more expensive, for domestic air conditioning, uses the minute-pressure difference controller that cost is increased greatly, so substantially need not in the family expenses air-conditioning.
So how to use the simplest method, use lower cost, energy savings can be controlled defrost again well again, is the problem that our refrigeration air-conditioner circle generally is concerned about.
Summary of the invention
For overcoming the shortcoming of several defrosting control methods commonly used in the above-mentioned prior art, the present invention proposes a kind of method of controlling the defrost of air-cooled heat pump air-conditioning by mensuration evaporator outlet wind speed.
The present invention has at first carried out analogue simulation to the air-cooled heat pump air-conditioning, sets up off-premises station, indoor set, the simulation model of compressor and restricting element, then by pressure balance, mass balance and energy balance are coupled to system with four big parts, loop iteration then, system carries out frosting operation simulation calculation.Finally obtained evaporating temperature and outlet respective relationships:
t 0=0.1417v 5-0.5463v 4+ 0.6173v 3-0.0988v 2In+0.4941v-4.9040 (1) formula, t 0Be evaporating temperature, ℃; V is evaporator outlet wind speed, m/s.
Then, at off-premises station evaporator outlet place air velocity transducer is installed, in the regular hour step-length, the wind speed substitution formula 1 with measuring obtains evaporating temperature t 0
Defrosting control method commonly used all is to determine whether defrost according to the evaporator surface temperature, on the engineering, and when the evaporator surface temperature reaches-2 ℃~-3 ℃, the beginning defrost.And there are relation of plane down in evaporating temperature and evaporator surface temperature:
t w=t 0+ Δ t w(2) in the formula, t wBe the evaporator surface temperature, ℃; Δ t wPoor for evaporating temperature and evaporator surface temperature generally got Δ t w=1.5~2 ℃.
The present invention continues to use this method, sets when the evaporator surface temperature t wWhen being reduced to-2 ℃~-3 ℃, the beginning defrost is set t such as us wBegin defrost when being reduced to-3 ℃.Work as the evaporating temperature that formula 1 calculates so, substitution formula 2 is such as getting Δ t w=1.5 ℃, obtain the evaporator surface temperature, then work as t wBegin defrost when reaching-3 ℃.
Defrost is determined according to different systems the finish time.According to engineering experience, general off-premises station outlet wind speed is 1.8m/s~2.2m/s when frost-free normally moves.According to this velocity interval, set a threshold value that finishes defrost, such as setting when wind speed end defrost during greater than 1.8m/s.
Sum up above introduction, the concrete control method of the present invention is as follows:
1) off-premises station, indoor set, compressor and the restricting element of air-cooled heat pump air-conditioning are set up simulation model respectively;
2) according to pressure balance, mass balance and principle of energy balance, system is carried out frosting operation simulation calculation, draw the evaporator evaporation temperature and the evaporator outlet respective relationships is as follows:
t 0=0.1417v 5-0.5463v 4+0.6173v 3-0.0988v 2+0.4941v-4.9040
3) at the off-premises station evaporator outlet air velocity transducer is installed;
4), set Δ t according to different systems wValue and t wThreshold value
5) when air-cooled heat pump moves, the wind speed substitution formula 1 that in the regular hour step-length air velocity transducer is measured obtains evaporating temperature t 0
6) the evaporating temperature t that formula 1 is calculated 0Substitution formula 2 obtains the evaporator surface temperature t w
7) judge the evaporator surface temperature t of calculating wThe value whether arrival presets;
8) if reach the value that presets, the beginning defrost; If do not reach, continue operation;
9) after the beginning defrost, when the wind speed that measures reaches the threshold value that presets, finish defrost, otherwise continue defrost.
Above-mentioned defrosting control method, not only simple, and can well energy savings, unlike time control defrost defrost like that regularly, just needing ability defrost under the situation of defrost; Also unlike temperature difference control defrost, be difficult to initialization, also insensitive to the variation of air conditioner load; Compare with minute-pressure difference control defrost simultaneously, cost is also very low.Can use very low cost, better controlled defrost.
The specific embodiment of the invention:
Come control method of the present invention is further described below in conjunction with a concrete heat pump air conditioner example.
1) off-premises station (finned-tube evaporator), indoor set (plate type heat exchanger), compressor (15hp piston compressor) and the restricting element (heating power expansion valve of refrigerating capacity 42kw) of JFLSR-350 air-cooled heat pump are set up the mathematical simulation model respectively;
2) according to pressure balance, mass balance and principle of energy balance, above-mentioned each parts are coupled to system, then system is carried out frosting operation simulation calculation, draw evaporating temperature and the evaporator outlet respective relationships is as follows:
t 0=0.1417v 5-0.5463v 4+0.6173v 3-0.0988v 2+0.4941v-4.9040
3) air velocity transducer is installed in off-premises station (finned-tube evaporator) exit;
4) according to the actual conditions of native system, set Δ t w=1.5 ℃, t w=-3 ℃, i.e. t wBegin defrost in the time of<-3 ℃;
5) when heat pump brings into operation, getting time step is 2min, and just every 2min air velocity transducer is measured wind speed once, and the wind speed substitution formula 1 with measuring obtains evaporating temperature t 0
6) the evaporating temperature t that formula 1 is calculated 0Substitution formula 2 obtains the evaporator surface temperature t w
7) judge the evaporator surface temperature t of calculating wWhether less than-3 ℃;
8) if t wWhen being less than or equal to-3 ℃, the beginning defrost if do not reach, continues operation;
In the native system, when the wind speed v that a certain moment air velocity transducer measures is 0.7m/s, formula 1 calculate t 0=-4.502 ℃, substitution formula 2 calculate t w=-3.002 ℃<-3 ℃, this moment, heat pump began defrost;
When 9) native system did not have frosting, normal wind speed was 1.8-2.1m/s, therefore sets and finish defrost when wind speed reaches 1.8m/s;
10) after the beginning defrost,, finish defrost, otherwise continue defrost when the wind speed v that measures is greater than or equal to 1.8m/s.

Claims (1)

1, a kind of air-cooled heat pump air-conditioning defrosting control method is characterized in that this control method comprises:
1) the air-cooled heat pump air-conditioning is carried out analogue simulation, set up off-premises station, indoor set, the simulation model of compressor and restricting element;
2) according to pressure balance, mass balance and principle of energy balance, system is carried out frosting operation simulation calculation, draw the evaporator evaporation temperature and the evaporator outlet respective relationships is as follows:
t 0=0.1417v 5-0.5463v 4+0.6173v 3-0.0988v 2+0.4941v-4.9040
3) at the off-premises station evaporator outlet air velocity transducer is installed;
4), set Δ t according to specific system wValue and t wThreshold value (as Δ t w=1.5 ℃, t w=-3 ℃); Wind speed threshold value (as 1.8m/s) when setting-up time step-length (as 2min) and normal operation;
5) when air-cooled heat pump brings into operation, the wind speed substitution formula 1 that in time step air velocity transducer is measured obtains evaporating temperature t 0
6) the evaporating temperature t that formula 1 is calculated 0Substitution formula 2 obtains the evaporator surface temperature t w
7) judge the evaporator surface temperature t of calculating wThe value whether arrival is set;
8) if t wReach the value of setting, the beginning defrost; If do not reach, continue operation;
9) after the beginning defrost, when the wind speed v that measures reaches preset threshold (such as greater than 1.9m/s), finish defrost, otherwise continue defrost.
CN 03116149 2003-04-03 2003-04-03 Air-cooled heat pump air-conditioning frost-melting controlling method Expired - Fee Related CN1206496C (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101984311A (en) * 2010-08-23 2011-03-09 江苏天舒电器有限公司 Hot-water frost preventing and defrosting device with compressor cooling
CN102779217A (en) * 2012-08-06 2012-11-14 大连三洋压缩机有限公司 Computer simulation performance computation method of refrigeration system under frosting working condition
CN105042791A (en) * 2015-08-20 2015-11-11 苏州创时云能源科技有限公司 On-line monitoring and controlling system and method for defrosting of air conditioner
CN105333577A (en) * 2015-11-23 2016-02-17 广东美的制冷设备有限公司 Air conditioner defrosting control method and device
CN105737389A (en) * 2014-12-10 2016-07-06 青岛经济技术开发区海尔热水器有限公司 Efficient defrosting method and device implementing control according to fan speed and pressure
CN106996675A (en) * 2016-01-22 2017-08-01 广州市美控电子科技有限公司 refrigeration temperature control intelligent defrosting control device
CN109312953A (en) * 2016-08-22 2019-02-05 株式会社电装 Air-cooling apparatus and humidifying/dehumidifying apparatus
CN109923357A (en) * 2016-11-10 2019-06-21 Lg电子株式会社 Refrigerator and its control method
CN111707028A (en) * 2020-07-14 2020-09-25 南京安纳杰能源科技有限公司 Outdoor air-cooled defroster of heat pump air conditioner
CN112050368A (en) * 2019-06-07 2020-12-08 青岛海尔空调器有限总公司 Control method and device for defrosting of air conditioner, air conditioner and server

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101984311B (en) * 2010-08-23 2013-04-24 江苏天舒电器有限公司 Hot-water frost preventing and defrosting device with compressor cooling
CN101984311A (en) * 2010-08-23 2011-03-09 江苏天舒电器有限公司 Hot-water frost preventing and defrosting device with compressor cooling
CN102779217A (en) * 2012-08-06 2012-11-14 大连三洋压缩机有限公司 Computer simulation performance computation method of refrigeration system under frosting working condition
CN105737389B (en) * 2014-12-10 2019-06-18 青岛经济技术开发区海尔热水器有限公司 A kind of efficient defrost method and device of combination fan speed and pressure control
CN105737389A (en) * 2014-12-10 2016-07-06 青岛经济技术开发区海尔热水器有限公司 Efficient defrosting method and device implementing control according to fan speed and pressure
CN105042791A (en) * 2015-08-20 2015-11-11 苏州创时云能源科技有限公司 On-line monitoring and controlling system and method for defrosting of air conditioner
CN105042791B (en) * 2015-08-20 2017-11-28 苏州创时云能源科技有限公司 A kind of air-conditioner defrosting on-line monitoring and control system and method
CN105333577A (en) * 2015-11-23 2016-02-17 广东美的制冷设备有限公司 Air conditioner defrosting control method and device
CN106996675A (en) * 2016-01-22 2017-08-01 广州市美控电子科技有限公司 refrigeration temperature control intelligent defrosting control device
CN109312953A (en) * 2016-08-22 2019-02-05 株式会社电装 Air-cooling apparatus and humidifying/dehumidifying apparatus
CN109923357A (en) * 2016-11-10 2019-06-21 Lg电子株式会社 Refrigerator and its control method
CN109923357B (en) * 2016-11-10 2022-04-01 Lg电子株式会社 Refrigerator and control method thereof
US11384975B2 (en) 2016-11-10 2022-07-12 Lg Electronics Inc. Refrigerator and control method thereof
CN112050368A (en) * 2019-06-07 2020-12-08 青岛海尔空调器有限总公司 Control method and device for defrosting of air conditioner, air conditioner and server
CN112050368B (en) * 2019-06-07 2022-07-15 重庆海尔空调器有限公司 Control method and device for defrosting of air conditioner, air conditioner and server
CN111707028A (en) * 2020-07-14 2020-09-25 南京安纳杰能源科技有限公司 Outdoor air-cooled defroster of heat pump air conditioner

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