Experimental and computational evaluation of temperature difference of a cascade condenser of R134a-R23 cascade refrigeration system

Rupesh, P. L.; Babu, J. M.; Surryaprakash, D.; Misra, Rahul

doi:10.1109/icstm.2015.7225494

Cited by 5 publications

(2 citation statements)

References 5 publications

(6 reference statements)

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“…Citarella et al 11 achieved an increase of 7% in COP by using the two-stage flash gas removal configuration as compared with the case without gas bypass. Several researchers also studied the optimal condenser temperature of the two-stage cycles using ammonia, carbon dioxide [15][16][17][18] , R404A 19 , R134a 20 . Högberg and Berntsson investigated single and two-stage heat pumps using non-azeotropic mixtures and pure working fluids 21 .…”

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confidence: 99%

A flexible heat pump cycle for heat recovery

McKeown

Ouderji

et al. 2022

Commun Eng

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Heat pumps will play a key role in transitioning domestic heating to fossil-free sources. However, improvement in energy efficiency and cost reduction are still needed. Current vapour-compression heat pumps are built upon the Evans-Perkins cycle which was originally designed for refrigeration applications. Once hot liquid refrigerant has transferred energy to the central heating system, it leaves the condenser with sensible heat which can be utilized. Here we report a modified and flexible Evans-Perkins heat pump cycle integrating heat recovery and storage which is then used as an ancillary heat source for the heat pump’s operation. It operates in a quasi-two-stage mode to theoretically save up to 20% in compressor power consumption compared with single-stage cycles. We build a prototype with off-the-shelf parts and demonstrate a practical 3.7% power saving at a heat production temperature of 35 °C. Power saving will further increase with heat supply temperature. We also qualitatively show that hot refrigerant exiting the condenser can be directly used for defrosting the evaporator, providing additional energy saving.

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confidence: 99%

A flexible heat pump cycle for heat recovery

McKeown

Ouderji

et al. 2022

Commun Eng

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“…Table 2 summarizes a review of the recent literature on experimental works on cascade vapor compression systems, with publications spanning over a period of nearly a decade. Except for a heat pump, 13 for water heating purposes, and two setups for low-temperature refrigeration, 14,15 papers on refrigeration [16][17][18][19][20][21][22][23][24] report on evaporating temperatures (of the low-temperature cycle) within the range of −30℃ and −50℃, which is typical of operation of commercial and industrial refrigeration plants. Exceptionally, higher evaporating or heat source temperatures are also found, such as −5℃, 16 2℃, −20℃, 17 and −8℃.…”

Section: Literature Surveymentioning

confidence: 99%

Experimental comparison between R134a/R744 and R438A/R744 (drop‐in) cascade refrigeration systems based on energy consumption and greenhouse gases emissions

Queiroz

Ojeda

Amjad

et al. 2021

Energy Science & Engineering

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This experimental study evaluates the energy performance and climatic changes of a cascade cooling system operating with the R134a/R744 pairs (cooling capacity of 4.5-6 kW) and R438A/R744. In both cases, the low-temperature refrigerant, R744, operated under subcritical conditions. The experimental apparatus basically consists of two vapor-compression cycles coupled by a plate cascade condenser. Two operational variables, from R744 cycle, were controlled: the degree-of-superheat and the compressor frequency. The experiment was initially assembled to pair R134a/R744. Subsequently, the R134a refrigerant charge in the high-temperature cycle was replaced by R438A, on a drop-in basis. The two systems, R134a/R744 and R438A/R744, were compared for similar cooling capacities and cold chamber air temperatures. Results showed that the energy consumption of the high-temperature compressor, operating with R438A, was higher than R134a for all tests. As a result, the COP values for R438A/R744 were 30% lower than those for R134a/R744. The greenhouse gases emissions of the two systems were evaluated using the total equivalent warming impact factor, TEWI, whose value for the R438A/R744 pair was approximately 29.5% higher, compared with R134a/R744. Since R438A was originally designed to substitute R22, a few comparative tests were carried out with the latter, always with R744 as the low-temperature cycle working fluid.

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