The utility of integrating photovoltaic (PV)-powered refrigerated warehouse operations with ice storage to enhance the storage and efficiency of cooling energy was explored. Researchers from China’s Yunnan Normal University investigated the effect of two types of ice storage modes on the performance of such facilities.

The study published in Results in Engineering compared both series-matching (SM) and parallel-matching (PM) ice storage as low-cost alternatives to the use of rechargeable storage batteries. In SM ice storage, the storage tank is connected in series to an air cooler to simultaneously enable the supply of cooling through the air cooler and storing cold energy in when solar energy is available. This arrangement supplies cooling during the night or when irradiance is insufficient. In the PM storage mode, the air cooler and ice storage tank are connected in parallel to maintain cold energy in the tank before supplying cooling when solar energy is available.

These ice storage options were tested in a refrigerated warehouse with a volume of 24,472 m3 that could operate either by PV or grid power. The PV system consisted of 5.4 kW of solar panels and an inverter, which operated the vapor compression refrigeration.

Under PV-SM operation, the refrigeration coefficient of performance (COP) was 2.47 under no load and 2.66 under full load. The PV-PM system displayed poorer results, with refrigeration COP of 2.26 under no load and 2.56 under full load. System Cop for PV-PM was 0.25 and 0.27, respectively. An additional benefit of SM mode was its lower cost relative to the PM mode, and it also proved superior to the PM mode in suppressing PV fluctuations.

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