Evaluation of Cooling Capacity of Refrigeration System with Limited Charge of R-290

Due to increased concerns of the global warming and corresponding regulatory requirement changes, demands of understanding and developing eco-friendly refrigeration system have continuously grown. Recently, natural refrigerants have received a significant attention as a future alternative because of their performance and environmentally friendly characteristics (No Ozone Depleting Potential, ODP and near zero Global Warming Potential, GWP). The present paper reports an experimental study performed with refrigeration systems developed using one of the natural refrigerants, R-290 (Propane &
$\text{GWP}=3$
), particularly with the limited charge amount to meet the most stringent regulatory requirement, IATA - Dangerous Goods Regulation (DGR). Two types of system were developed, so called Liquid Circulating Chiller (LCC) and Air-Air Cooler (AAC). Both were with air-cooled condensers. LCC consists of a liquid cooled evaporator while ACC comes with an air-cooled evaporator. All component selections were made to achieve the minimum refrigerant charge and as a result, the total system charge was kept around 100g or less. During the system development, several combinations of the components were considered (e.g., compressor and heat exchangers), and developed system was tested under various test conditions as a part of the system optimization. From the study, the maximum cooling capacity achieved was around 3.2kW and 2.6kW with less than 100g of R-290 refrigerant charge for LCC and AAC, respectively. In addition, the distribution of the charge within the system was estimated, which indicated that the condenser was one of the most refrigerant consumed components, followed by the compressor, the liquid line, and related components.