Heat Transfer, Refrigeration and Heat Pumps

The Special Issue entitled “Heat Transfer, Refrigeration and heat Pumps” accepted papers covering a wide range of topics related to heat pumps, thermal energy storage, and low-Global Warming Potential (GWP) alternative refrigerants [...]

Energy Analysis of Vapor Compression Refrigeration Cycle Using a New Generation Refrigerants with Low Global Warming Potential

An energy analysis study carried out on a vapor compression refrigeration cycle using refrigerants with low global warming potential (GWP) of the Hydro-Fluoro-Olefin (HFO) type, in particular R1234yf and R1234ze fluids to replace HFC refrigerants . Computer code was developed using software for solving engineering equations to calculate performance parameters; for this, three HFC type fluids (R134a, R404A and R410A) were selected for a comparative study. The results showed that R1234ze is the best refrigerant among those selected for the mechanical vapor compression refrigeration cycle. The thermodynamic analysis showed the effect of the evaporator temperature (-22 °C to 10 °C) and the condenser temperature (30 °C to 50 °C) on the steam cycle performance. Compression refrigeration, including the coefficient of performance. The results showed that the HFO-R1234ze with low GWP gives the best coefficient of performance of 3.14 close to that of the R134a fluid (3.17). In addition, R1234ze is considered an alternative fluid to R134a for their ecological properties.

The Operation Analysis of the Innovative MainBox Food Storage Device

The development and construction of a prototype device (food parcel locker), consisting of small cooling and freezing chambers (boxes) ensuring temperature conditions (+5 C or −18 °C), enabling food storage were carried out. The innovative solutions have been introduced in the MainBox device: the appropriate construction of the device (materials, cooling installation), properly functioning systems (control of chillers, security, temperature monitoring), and propane as refrigerant (high energy efficiency, low global warming potential). The risk of explosion has been eliminated by closing of the cooling installation and reducing of propane amount. The refrigeration unit has been adapted to work in external conditions by installing additional elements (pressure switches for compressor protection and for condensing pressure control). In real conditions, the operation of the innovative MainBox food storage device allowing the receipt of food products without having to wait for a supplier was verified. The temperature distribution in all chambers of the cooling and freezing module was investigated using a thermal imaging camera and a temperature monitoring system. The correct operation of MainBox devices was verified during their loading with food products that require specific temperature conditions during storage.