Results 101 to 110 of about 470 (129)
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Applied Thermal Engineering, 2012
Abstract For a space heating air source heat pump (ASHP) unit, when its outdoor coil surface temperature is below both the air dew point temperature and the freezing point of water, frost will form on its outdoor coil surface. Frosting affects its operational performance and energy efficiency. Therefore, periodic defrosting is necessary.
Shiming Simon Deng, Jiankai Dong
exaly +2 more sources
Abstract For a space heating air source heat pump (ASHP) unit, when its outdoor coil surface temperature is below both the air dew point temperature and the freezing point of water, frost will form on its outdoor coil surface. Frosting affects its operational performance and energy efficiency. Therefore, periodic defrosting is necessary.
Shiming Simon Deng, Jiankai Dong
exaly +2 more sources
Building and Environment, 2010
Abstract When an air-source heat pump (ASHP) unit is used for space heating at a low ambient temperature in winter, frost may be formed on its outdoor coil surface. Frosting affects its operational performance and energy efficiency, and therefore periodic defrosting is necessary.
Shiming Simon Deng, Minglu Qu
exaly +2 more sources
Abstract When an air-source heat pump (ASHP) unit is used for space heating at a low ambient temperature in winter, frost may be formed on its outdoor coil surface. Frosting affects its operational performance and energy efficiency, and therefore periodic defrosting is necessary.
Shiming Simon Deng, Minglu Qu
exaly +2 more sources
Energy Procedia, 2017 Abstract For an air source heat pump (ASHP) unit with a vertically installed multi-circuit outdoor coil, a reverse cycle defrosting (RCD) operation is always terminated when the tube surface temperature at the exit of the lowest circuit reaches a pre-set value. It is obviously that when the pre-set temperature is higher, the defrosting duration would
Mengjie Song +2 more
exaly +2 more sources
Applied Thermal Engineering, 2011
Abstract This paper reports on an experimental study on the operating performance for a novel reverse-cycle hot gas defrosting method for air source heat pumps (ASHPs). Firstly, a description of both an experimental prototype ASHP unit where the novel reverse-cycle hot gas defrosting method may be realized, and its operating modes are presented. This
Shiming Simon Deng, Minglu Qu
exaly +2 more sources
Abstract This paper reports on an experimental study on the operating performance for a novel reverse-cycle hot gas defrosting method for air source heat pumps (ASHPs). Firstly, a description of both an experimental prototype ASHP unit where the novel reverse-cycle hot gas defrosting method may be realized, and its operating modes are presented. This
Shiming Simon Deng, Minglu Qu
exaly +2 more sources
Science and Technology for the Built Environment, 2016
Defrosting outdoor coils of residential heat pumps in an energy efficient manner remains an active area of research in the HVAC industry. Inverting the cycle to reject heat from the outdoor coils is the most common method used currently. However, this method is energy intensive.
Kamalakkannan Muthusubramanian +3 more
openaire +1 more source
Defrosting outdoor coils of residential heat pumps in an energy efficient manner remains an active area of research in the HVAC industry. Inverting the cycle to reject heat from the outdoor coils is the most common method used currently. However, this method is energy intensive.
Kamalakkannan Muthusubramanian +3 more
openaire +1 more source
International Journal of Refrigeration, 2004
The effects of fan starting methods on the defrost performance in an air-source heat pump were investigated experimentally. Experiments were conducted on a 50 kW unitary air-to-water heat pump. The dynamic characteristics of both the coil fan pre-start and normal-start tests during the defrost cycle were discussed.
Dong Huang, Xiuling Yuan, Xingqun Zhang
openaire +1 more source
The effects of fan starting methods on the defrost performance in an air-source heat pump were investigated experimentally. Experiments were conducted on a 50 kW unitary air-to-water heat pump. The dynamic characteristics of both the coil fan pre-start and normal-start tests during the defrost cycle were discussed.
Dong Huang, Xiuling Yuan, Xingqun Zhang
openaire +1 more source
Reverse Cycle Defrosting Case Studies for Multicircuit Outdoor Coil
Mengjie Songexaly +2 more sources
Applied Thermal Engineering, 2017
Abstract It is universally acknowledged that the accumulation of frost on the evaporator surface will reduce the cooling capacity and performance of the cold storage. Therefore defrosting must be periodically and effectively carried out to avoid the evaporator blockage.
Dong Wang +4 more
openaire +1 more source
Abstract It is universally acknowledged that the accumulation of frost on the evaporator surface will reduce the cooling capacity and performance of the cold storage. Therefore defrosting must be periodically and effectively carried out to avoid the evaporator blockage.
Dong Wang +4 more
openaire +1 more source
Applied Energy, 2017
Abstract Air source heat pump units could efficiently recover low grade waste heat from ambient air for indoor air heating or hot water supplying, which makes them widely applied in recent decades. For a vertically installed multi-circuit outdoor coil, a reverse cycle defrosting operation is always used to solve its frosting problem at high humidity ...
Mengjie Song +2 more
exaly +2 more sources
Abstract Air source heat pump units could efficiently recover low grade waste heat from ambient air for indoor air heating or hot water supplying, which makes them widely applied in recent decades. For a vertically installed multi-circuit outdoor coil, a reverse cycle defrosting operation is always used to solve its frosting problem at high humidity ...
Mengjie Song +2 more
exaly +2 more sources
International Journal of Refrigeration, 2018
Abstract A thorough literature review indicates that there is a dearth of modeling studies on the defrosting dynamics of air source heat pumps (ASHPs) due to the complex underlying physics and numerous computation details. In an effort to bridge the research gap, this paper first presents a five-stage hot-gas defrost model which is incorporated into ...
Hongtao Qiao +2 more
openaire +1 more source
Abstract A thorough literature review indicates that there is a dearth of modeling studies on the defrosting dynamics of air source heat pumps (ASHPs) due to the complex underlying physics and numerous computation details. In an effort to bridge the research gap, this paper first presents a five-stage hot-gas defrost model which is incorporated into ...
Hongtao Qiao +2 more
openaire +1 more source