A new method of defrosting evaporator coils

Mader, Gunda; Thybo, Claus

doi:10.1016/j.applthermaleng.2012.01.033

Cited by 26 publications

(5 citation statements)

References 17 publications

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“…The defrosting methods mainly include hot water spray defrosting, electric heater defrosting, compressor shutdown, hot gas bypass and reverse‐cycle defrosting . A number of studies have experimentally investigated the defrosting methods and their effects . However, these defrosting methods are more or less inadequate.…”

Section: Introductionmentioning

confidence: 99%

“…5,8 A number of studies have experimentally investigated the defrosting methods and their effects. 20,21,30,34 However, these defrosting methods are more or less inadequate. Electric heater defrosting is simple and very easy to control and could obtain stable heating at the expense of extra electric energy, 17 but it was only applicable for window air conditioner with small capacity.…”

Section: Introductionmentioning

confidence: 99%

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Experimental study on the performance of air source heat pump system with multiple parallel outdoor units

Niu

2020

Int J Energy Res

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Summary This paper presents a novel air source heat pump for heating of buildings named air source heat pump with multiple parallel outdoor units (ASHPMO). Multiple outdoor units were connected in parallel with the aim of realising alternate defrosting and uninterrupted heating simultaneously. An experimental apparatus of the ASHPMO system was developed. The defrosting performance was experimentally investigated under different outdoor air temperatures, outdoor air relative humidity, and condensation temperatures, among other factors. The test results showed that the novel ASHPMO system could provide continuous heating when defrosting even under an outdoor air temperature of −10°C. Variations in compressor vapour suction and discharge pressure and temperature were observed. The minimum heating capacity could still reach 60% of that without defrosting. Under the defrosting condition with outdoor air temperature −10°C, both the heating coefficient of performance (heating COP) and total energy efficiency ratio (EER) of the system can reach to 2.0 and 2.32, respectively.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental study on the performance of air source heat pump system with multiple parallel outdoor units

Niu

2020

Int J Energy Res

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“…The defrosting techniques used in the HVAC&R industry may be adopted in GVR cooling system. Amer and Wang [21] and Hu et al [22] summarized defrosting methods as follows: (1) on-off cycling [23], (2) hot gas bypass [24][25][26], (3) reverse cycle [27][28], (4) electric resistive heating [29][30], (5) desiccants as dehumidifiers or ( 6) ultrasonic wave [31][32] and their combined methods [33][34][35]. Hot gas bypass (HGB) was employed here as the key candidate defrosting method instead of reverse cycle for simple structure [36].…”

Section: Introductionmentioning

confidence: 99%

“…3). In conventional HGB mechanism, the residual refrigerant inside evaporator was removed by evaporation during defrosting [17,30], which consumed the energy of hot gas [23]. Especially in low evaporating temperature conditions, this additional energy consumption will become more and even excessive.…”

Section: Introductionmentioning

confidence: 99%

A novel defrosting method in gasoline vapor recovery application

Liang

Sun

2018

Energy

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Condensation method is comprehensively applied for gasoline vapor recovery (GVR), of which frosts in the heat exchanger is the greatest challenge, especially for the continuous long running cases. A novel dual channel GVR cascade refrigeration system with shell-tube heat exchanger was presented and tested in this paper. With onework-one-standby evaporator settings, combined with refrigerant evacuation and delay switching strategies, the defrosting of low temperature shell-tube heat exchanger was analyzed and solved. Also multi-stage cycle was introduced to supply three cooling stage, which cooled the gasoline vapor from ordinary temperature to about -70°C. By the means of industrial application validation and process calculation, the ability of the non-stop cooling during defrosting was verified. The refrigerant evacuation was proposed to prevent high pressure drop caused by frost accumulation, which also improved the cooling capacity by 28.2% and approached the defrost efficiency of 55.4%. In addition, it was found that delay switching can effectively reduce the capacity fluctuation. Based on sensitivity studies, 20 minutes delay was identified as the best switching timing for this device. The capacity of this system performed lower reduction, higher duty ratio and defrost efficiency.

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“…Saidur et al [4] studied the effects of room temperature, door opening, and thermostat installation position on the energy consumption of refrigerators. Mader and Thybo [5] studied evaporator coils for air heat pumps. Results showed that the below-standard frost state of the evaporator can eliminate frost, and also other states were more efficient.…”

Section: Introductionmentioning

confidence: 99%

Energy Consumption of Defrosting Process in No-Frost Refrigerators

Ünal¹

2018

Journal of Thermal Engineering

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Refrigerators have high energy consumption because they consume energy throughout the day, and they are used in all residences and in most offices. Designing more efficient models and, thus, decreasing the energy consumption of refrigerators have become necessary, owing to the global energy scarcity. The purpose of this study was to decrease energy consumption and increase the efficiency of the defrosting process in no-frost refrigerators. The defrosting process plays an important role in the energy consumption of no-frost refrigerators. The amount of energy needed for defrosting and the time it takes are important factors for manufacturers in terms of energy performance. Recently, a theoretical correlation was developed as a function of the frost thickness, heat flux, and frost density for estimating the defrosting time of an evaporator fin surface. The melting time of the frost on the fin was calculated by a mathematical model and compared to results that were obtained experimentally. The results were differed from the actual melting time as 4.7%.

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A new method of defrosting evaporator coils

Cited by 26 publications

References 17 publications

Experimental study on the performance of air source heat pump system with multiple parallel outdoor units

Experimental study on the performance of air source heat pump system with multiple parallel outdoor units

A novel defrosting method in gasoline vapor recovery application

Energy Consumption of Defrosting Process in No-Frost Refrigerators

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