Experimental Study on Characteristics of False Defrosting for Split Air Source Heat Pump

Detailed experimental study on the characteristics of false defrosting of a split type air-source heat pump (ASHP) has been made. The results show that the false defrosting is seriously detrimental to ASHP by comparing varied parameters of compressor such as shaft power, suction and discharge pressure, etc. in normal defrosting and false defrosting. This paper also analyzes a common defrosting control method for air conditioner of split ASHP room, i.e., with two temperature sensors set on indoor heat exchanger, the operating principle thereof and drawbacks in terms of causing false defrosting.

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EXPERIMENTAL STUDY ON A NOVEL DEFROST CYCLE FOR AIR SOURCE HEAT PUMP

International Journal of Air-Conditioning and Refrigeration ◽

10.1142/s2010132510000095 ◽

2010 ◽

Vol 18 (01) ◽

pp. 77-84 ◽

Cited By ~ 2

Author(s):

XIAN-MIN GUO ◽

YA-JING WANG ◽

WEN-CHENG FU ◽

XIANG-CHENG TAO

Keyword(s):

Experimental Study ◽

Heat Exchanger ◽

Heat Pump ◽

Capillary Tube ◽

Experimental Results ◽

Indoor Space ◽

Mechanical Impact ◽

Hot Gas ◽

Switching Times ◽

Air Source Heat Pump

On the basis of the hot-gas bypass defrost cycle, a new defrost method for air source heat pump is proposed. In the new defrost cycle, the outdoor heat exchanger is divided into two parts which are connected by a capillary tube. The front and rear parts of the heat exchanger are used as the evaporator and condenser respectively during defrosting, and can be defrosted orderly by using the four-way valve. The defrosting performance of the new cycle is investigated experimentally and the results are compared with that of the reverse-cycle defrost system. The experimental results indicate that the energy is used more efficiently in the new defrost cycle, therefore, the defrosting duration and losses are less than those of the reverse-cycle defrost system. Moreover, it does not extract heat from the indoor space during defrosting in terms of the new defrost cycle. Compared with the reverse-cycle defrost system, it is found that the switching times of the four-way valve in the new defrost system are the same, and the fluctuation of the discharge and suction pressures during the defrosting is much less than that in the reverse-cycle defrosting, hence, the mechanical impact on the system is much less.

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Experimental study on vapor injection air source heat pump with internal heat exchanger for electric bus

Energy Procedia ◽

10.1016/j.egypro.2019.01.817 ◽

2019 ◽

Vol 158 ◽

pp. 4147-4153 ◽

Cited By ~ 1

Author(s):

Xinxin Han ◽

Huiming Zou ◽

Hongbo Xu ◽

Changqing Tian ◽

Wei Kang

Keyword(s):

Experimental Study ◽

Heat Exchanger ◽

Heat Pump ◽

Internal Heat ◽

Air Source Heat Pump ◽

Internal Heat Exchanger ◽

Electric Bus ◽

Vapor Injection

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AN EXPERIMENTAL STUDY ON PERFORMANCE IMPROVEMENT FOR AN AIR SOURCE HEAT PUMP BY ALTERNATE DEFROSTING OF OUTDOOR HEAT EXCHANGER

International Journal of Air-Conditioning and Refrigeration ◽

10.1142/s2010132514500175 ◽

2014 ◽

Vol 22 (03) ◽

pp. 1450017 ◽

Cited By ~ 8

Author(s):

HOON JUNG ◽

JUNGHO HWANG ◽

CHANGDUK JEON

Keyword(s):

Experimental Study ◽

Heat Exchanger ◽

Low Temperature ◽

Performance Improvement ◽

Heat Pump ◽

Heating Surface ◽

Coefficient Of Performance ◽

Space Heating ◽

High Humidity ◽

Air Source Heat Pump

For a space heating air source heat pump (ASHP) in the condition of low temperature and high humidity, frost on the surface of heat exchanger becomes the major cause decreasing heating surface area and thus the performance of heat pump. In this study, we showed a method of delaying the implantation of frost using alternate defrost control. First, we acquired the performance data for conventional periodic reversed-cycle defrosting with a 5RT heat pump. After the experiment, the heat pump was modified to verify the effects of newly introduced alternate defrosting and compared with the conventional periodic reverse cycled method. It was found that heating coefficient of performance (COP) of heat pump using newly proposed alternate defrost method was about 17% higher than conventional heat pump using periodic reverse cycled defrosting.

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