Similarity model for predicting the performance of an R718 compressor

A general compression refrigeration system consists of a compressor, condenser, pressure-reducing valve, and evaporator to induce phase changes in the refrigerant. The performance of the compression refrigeration system strongly depends on the type and characteristics of the refrigerant. However, synthetic refrigerants such as chlorofluorocarbon, hydrochloro-fluorocarbon, and hydrofluorocarbon directly affect the environment as greenhouse gases and indirectly affect the environment by generating substances as they decompose. Thus, researchers have been focusing on developing refrigerants with a low or zero global warming potential. R718 (i.e. water) is an ecofriendly refrigerant, but its specific volume rapidly changes between the liquid and gas phases. This requires making the components of the compression refrigeration system larger than normal to accommodate these volume changes, which is inefficient for manufacturing prototypes. In this study, an alternative refrigerant was applied to the design of a centrifugal compressor that uses R718 as the working fluid. To address the volume change of R718, a numerical analysis was conducted by using the similarity method, where the size of the impeller was reduced and the rotational speed was controlled. To ensure the reliability of the similarity model, its results were compared against the experimental data of the original model for verification.

Aspects of adapting the cooling installation in a food cold storage system to the applicable f-gas regulations

The paper presents the methodology of the analysis of the cooling system reconstruction in a food cold store under the regulations applicable from the beginning of 2020. They result from the so-called the F-Gas Act concerns the use of refrigerants with a low environmental impact. First, the elements of the existing regulations on the use of refrigerants were discussed. This part of article focus mainly on the F-Gas Act and the regulations it entails. Then, the refrigerants used so far in refrigeration systems were compared with substitutes, which were the only ones that have been approved for use since 2020, thanks to the low GWP index. Their properties are briefly described, along with the benefits (primarily for the environment) of their use. The main part of the work is the analysis of the reconstruction of the cooling system to use an alternative refrigerant. During the work, the construction of the cold storage was analyzed together with the system currently working in analysed location. Then, the heat balance was calculated, thanks to which it was possible to determine the demand for cold. Than, several refrigerants that meet the latest standards and application regulations were selected. Their operating parameters were examined, the possible variants of use were compared in relation to the determined demand for cooling and the most important operational features were summarized.

Investigation and Analysis of Green Refrigerant Zero ODP as an Alternative Refrigerant Lower Cost and GWP

This research presents the results of investigation and analysis of the environmentally friendly refrigerant for R22 replacement. All refrigerant properties in this research were based on results from the REFPROP and CYCLE_D-HX software of NIST under CAN/ANSI/AHRI540. The results of this work show that HCs R170, R290, R600, R600a, R601, R601a, R1150 and R1270 can be mixed in HFCs R417A, R417B, R422A, R422B, R422C, R422D, R424A, R437A, R438A and R453A and able to be further developed in the future. All refrigerants are non-flammable refrigerants, non-toxic and zero ODP. The R453A mixed with HCs R600 (0.6%) and R601a (0.6%) and is COPc refrigerant close to that of R22 refrigerant. In conclusion, it can be used as an environmentally friendly and energy efficiency replacement for R22. All refrigerants are also refrigerants that are matched with the 4th generation refrigerants with the use of natural refrigerants.

Experimental modeling of refrigerants at high ambient temperature

High ambient temperature is well known to have an adverse impact on air conditioners; it lowers their cooling capacity along with their coefficient of performance. Moreover, air conditioning plays a significant role in damaging the environment as it contributes to both global warming and ozone depletion. In the past few decades, the Montreal agreement was introduced to protect the ozone layer from substances that contribute to its depletion. Developing countries are now facing the challenges of phasing out HCFCs such as R22 in the air conditioning sector. The aim of this study is to find an alternative refrigerant that can replace R22 after its phase out. The new refrigerant must have low environmental impacts and should be able to withstand operation in high ambient temperature countries. In this study, the hydrocarbon refrigerant R290 and the hydrofluorocarbon R410A were selected as alternatives. Furthermore, experimental testing was carried out on the baseline refrigerant R22 and R410A using a 7kW ducted split unit at three outdoor conditions: 35oC, 48oC, and 52oC. From the experimental results, a model based on R22 and R410A was developed using Engineering Equation Solver (EES). The model was successful in verifying the experimental results within a 15% error range and was tested again with external data from (Eltalouny & Nielsen, 2016) [10]. After confirming its validity, the model was simulated to predict the performance of the alternative refrigerant R290 under the same experimental conditions and input data. To test the model’s validity on R290, results from Eltalouny & Nielsen (2016) were used. The model succeeded in predicting the COP and power consumption. The refrigerants demonstrated deterioration in their performance at elevated temperatures compared to their performance at a typical operating regime. With proper safety measures, and enhancement to the compressor efficiency, R290 can be considered as a promising alternative.

Case study of liquid suction heat exchanger in a mechanical refrigeration system using alternative refrigerants

This paper investigates the effect of adding a liquid-suction heat exchanger on the performance of a mechanical refrigeration system using alternative refrigerants. Engineering Equation Solver (EES) was used to simulate a mechanical refrigeration system in two configurations: modified system with liquid-suction heat exchanger and system without liquid-suction heat exchanger. The results revealed that the liquid-suction heat exchanger has a significant effect on the system performance as it influences the subcooling and superheating temperatures. The results also showed that the highest value of the coefficient of performance (COP) was achieved by the modified system with refrigerant type R134a, COP was about 7% and 12% higher than that of refrigerants R600a and R22 respectively. It also presented that R600a has high response to increase the refrigerant effect when the liquid-suction heat exchanger is used. R600a is good alternative refrigerant and it can be used in the mechanical refrigeration system, but its COP is lower than that of R134a.