Comparative analysis of a cooling systems working on an environmentally friendly refrigerants

The paper treats with refrigerants which affect on excessive heating of atmosphere. They are in group offluorinated greenhouse gases which are regulated by European and polish law. The main aim is to lower their amount in industry leading to overall removal from use. We present possible way to design refrigeration system lowering their adverse effect on natural environment. So three options of cooling systems are analyzed: one-stage refrigeration system working with R449A, cascade refrigeration system with R744 (carbon dioxide)/ R134a and R717 (ammonia) refrigeration plant. Due to the nowadays raising use of the cascade systems, an analysis of the operating parameters of such installation was carried out with considering the cascade heat exchanger as a condenser/evaporator. The installations concerned are three alternative offers for meat processing manufactory. A thermal balance was prepared for chambers located in building and the operating parameters of the installation were assumed. The equipment corresponding to the required cooling capacities were selected.

Performance analysis of a novel cascade vapor compression system for small-scale desalination and cooling

The demand for improving living standards has led to increasing freshwater consumption and comfort cooling, requiring significant performance improvements. In this regard, a novel and efficient cascade refrigeration system for simultaneous generation of considerable freshwater and cooling amounts is proposed. The system does not require dedicated components for desalinating seawater because they are dual-purpose. Utilizing the cascade configuration enhances energy efficiency by lowering the compression work while improving energy recovery by utilizing existing heat to vaporize seawater for desalination. A mathematical model of the innovative system based on thermodynamic and economic principles has been developed and utilized to predict the proposed system's thermal performance and cost savings. A comprehensive analysis has been conducted to study the effect of multiple parameters such as the evaporator, condenser, and brine boiling temperatures. The main studied parameters were COP, GOR, freshwater production, and total cost savings. For a 10 TR unit, the freshwater production was between 56.11 – 73.36 kg/h, with cost savings reaching 2,226 US$/yr. It was found that the freshwater production increased with condenser and brine boiling temperature but decreased with evaporator temperature. The COP improvement can be as much as 26% over the reference cooling system without desalination.

Experimental Analysis of the R744/R404A Cascade Refrigeration System with Internal Heat Exchanger. Part 1: Coefficient of Performance Characteristics

This study evaluates the performance of an R744/R404A cascade refrigeration system (CRS) with internal heat exchangers (IHE) in supermarkets. R744 is used as the refrigerant in a low-temperature cycle, and R404A is used as the refrigerant in a high-temperature cycle. In previous studies, there are many studies including theoretical performance analysis of the CRS. However, experimental studies on the CRS are lacking, and experimental research on the R744/R404A system with an IHE is scarce. Therefore, this study provides basic data for optimal refrigeration system design by experimentally evaluating the results of modifying various parameters. The operating parameters considered in this study include subcooling and superheating, condensing and evaporating temperature, cascade evaporation temperature, and IHE efficiency in the R744 low- and R404A high-temperature cycle. The main results are summarized as follows: (1) By applying the results of this study, energy efficiency is achieved by optimizing the overall coefficient of performance (COP) of the CRS, and the refrigerant charge of the R404A cycle is minimized and economic efficiency is also obtained, enabling operation and maintenance as an environment-friendly system. (2) When designing the CRS, finding the cascade evaporation temperature that has the optimum and maximum COP according to the refrigerant combination should be considered with the highest priority.