Performance evaluation of a laboratory-scale cooling system as a household refrigerator with phase change materials

ABSTRACT

In this study, a laboratory-scale cooling system, simulating a household refrigerator, was examined experimentally for an average cabinet temperature of 4°C with two different types of phase change materials (PCMs) (water and eutectic solution). The system was tested with various amounts of water and different concentrations of sodium sulfate (Na₂SO₄) in water. The influence of different amounts and types of the PCMs on the cabinet air temperature and compressor power consumption was analyzed during the running period. The cabinet air temperature change over time was also observed during the power failure period. The examinations suggest using 1.0 wt.% Na₂SO₄ solution as the PCM in the cooling systems. This solution provides the lowest energy consumption (19.5 kJ), and the running time percentage (21.7%); while maximizing the energy saving (14.2%). In addition, integrating it as PCM could allow preserving products for long periods without significant quality loss during a power failure; because it prevented the rapid increase of the cabinet air temperature in this scenario. Lastly, when the cycle frequency is considered, it has the best time interval and the number of cycles (5.3). Thus, it has a positive effect on reducing the compressor cycling frequency, which eventually increases the compressor lifespan.

KEYWORDS:

• Cooling system
• energy consumption
• household refrigerator
• phase change material
• power failure

Nomenclature

PCMphase change material

TES thermal energy storage

COP coefficient of performance

RSM response surface methodology

BEHS binary eutectic hydrated salt

w/PCM with phase change material

wo/PCM without phase change material

Symbols

M mass (kg)

wt.% weight percentage

ttime [h]

t_oncompressor on time [min]

t_offcompressor off time [min]

T temperature [°C]

Vvolume (mL)

$W_{PCM}$ total energy consumption with PCM [kJ]

$W$ total energy consumption without PCM [kJ]

W(t)compressor energy consumption [kJ]

Wpower [kW]

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Bercem Kiran-Yildirim

Bercem Kiran-Yildirim received her B.Sc., M.Sc., and Ph.D. degrees in Chemical Engineering at Marmara University. She studied at Thermal Process Technology Laboratory, Martin Luther University, for approximately six months. She was a Guest Researcher at the Institute of Process Engineering in Life Sciences, Section I: Food Process Engineering, Karlsruhe Institute of Technology between 07.2018-12.2019. She has been working as a faculty member at Marmara University since 2008. She is currently with the Department of Chemical Engineering as an Assistant Professor. Her research interests are in the fields of crystallization, recrystallization, adsorption, phase change materials, refrigeration systems, and energy consumption.