Thermodynamic Analysis and Effects of Replacing HFC by Fourth-Generation Refrigerants in VCR Systems

The third-generation refrigerants belonging to hydrofluorocarbons (HFCs) do not contribute to ozone depletion. However, HFCs are listed as greenhouse gases by Kyoto Protocol because of their relatively high global-warming potential (GWP). At present the research is now mainly focused on refrigerants with zero ozone depletion potential (ODP) and less GWP, which are termed as Fourth generation refrigerants. This paper analyzes the advancement in refrigerants, and presented the different options in choosing a refrigerant with respect to international agreements to curb the stratospheric ozone depletion and global warming. The hydrofluoroolefins (HFOs) i.e., fourth generation refrigerants are available in limited quantities and also their performance is not completely tested in different applications. Hence this paper aims at assessing the performance of fourth generation refrigerants in terms of their mass flow rate requirement and COP for a specified cooling load and compared with the existing third generation refrigerants in usage. It is found that fourth generation refrigerants COP is low and mass flow rate and power requirements are high. However, HFO1234ze(E) can replace R134a as its performance is almost similar to R134a with an added advantage of low GWP.

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Standard Rating Charts for Low Global Warming Potential Refrigerants Flowing Through Adiabatic Helical Capillary Tube

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4043386 ◽

2019 ◽

Vol 11 (5) ◽

Author(s):

Badrish Pandey ◽

Desireddy Shashidhar Reddy ◽

Mohd. Kaleem Khan ◽

Manabendra Pathak

Keyword(s):

Global Warming ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Global Warming Potential ◽

Capillary Tube ◽

Prediction Algorithm ◽

Mean Deviation ◽

Coil Diameter ◽

Low Global Warming Potential

The present research work is undertaken to develop ASHRAE like standard rating charts for currently used refrigerants R-134a and R-410A and their potential low global warming potential (GWP) substitutes R-1234yf and R-32, respectively. A self-adjustable mass prediction algorithm has been developed using an averaging technique. Based on this, a matlab code dynamically linked to refprop v. 9.0 software has been developed that solves governing equations of mass, momentum, and energy. Two-phase flow inside the capillary tube is assumed homogeneous and metastability is ignored in the proposed model. The proposed numerical models are in good agreement with the available experimental data with overall percentage mean deviation is less than 6%. Coil diameter plays an important role in adjusting the mass flow rate in the helical capillary tube. Coiling of capillary tube causes an increase in friction pressure drop and a reduction in refrigerant mass flow rate. It has been found that the mass flow rate reduces by about 5% as coil diameter is reduced from 120 to 20 mm.

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Performance Comparison of Automotive Air Conditioner Using Various Refrigerants

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1125.561 ◽

2015 ◽

Vol 1125 ◽

pp. 561-565

Author(s):

Vina Serevina ◽

Sumeru ◽

Azhar Abdul Aziz ◽

Henry Nasution

Keyword(s):

Global Warming ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Compression Ratio ◽

Cooling Capacity ◽

Performance Comparison ◽

Working Fluid ◽

Air Conditioner ◽

Ambient Temperatures

Working fluid of R134a is widely used as a refrigerant in automotive air conditioner. This refrigerant has a good performance on the automotive air conditioner. However, because R134a still has a high global warming potential, this refrigerant must be reduced and replaced by environmentally friendly refrigerants. Hydrocarbons of R600a, R290 and their mixtures are widely used as substitute refrigerant. These refrigerants are natural fluids, no effect on the climate, inexpensive and readily available. There are three performances will be discussed in the present study, namely COP, mass flow rate and compression ratio. The present study investigates the effect of three refrigerants, i.e. R134a, R600a and R290 on the performance of automotive air conditioner. The results show that the COP of R600a is higher than those R134a and R290. For the same cooling capacity, the mass flow rate of R600a is approximately 50% of R134a for all ambient temperatures. In addition, the compression ratio of R600a is lower than that of R134a.

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