A novel exergy based charge optimisation for a mobile air conditioning system

Proceedings of the Institution of Mechanical Engineers, Part E:

Lal

2020

In view of promoting the utilization of solar photo-voltaic energy for milk chilling application a custom designed milk chiller with DC compressors was fabricated. Two different DC compressors were used operating with HFC-134a and HC-600a refrigerants to ascertain the performance of HFC and HC refrigerants when used in solar powered application. In view of optimizing the performance of both refrigerants, charge optimization was experimentally carried out for both refrigerant circuits. The optimum charge was obtained based on the maximum coefficient of performance and exergy efficiency. When comparing ice formation and coefficient of performance, the HC-600a refrigerant circuit was lower than that of HFC-134a circuit. It was also observed that the total exergy destruction experienced was maximum in the HFC-134a circuit than that of the HC-600a circuit. The magnitude of exergy destruction was found to be maximum in the compressor and then followed by the condenser, evaporator and finally the capillary for both refrigeration circuits. This study showed an efficient way for using the solar power for operating a milk chiller with DC compressors and with ice bank tank to avoid the dependency on batteries.

Section: Effect Of Refrigerant Charge On the Exergetic Performance Of The Systemsupporting

confidence: 87%

Charge optimisation of a solar milk chiller with direct current compressors

Proceedings of the Institution of Mechanical Engineers, Part E:

Lal

2020

“…The actual COP of the system is defined as the ratio between the system cooling capacity and power consumption by the compressor motor 31 where, Q evap is the cooling capacity of the evaporator and W ele the electrical power consumed by the compressor was taken from the power meter. where, m· ref is the mass flow rate of refrigerant in kg.s −1 , h evap,in and h evap,out are the refrigerant enthalpies at evaporator inlet and outlet in kJ.kg −1 respectively.…”

Section: Data Reductionmentioning

confidence: 99%

Experimental studies on the performance of mobile air conditioning system using environmental friendly HFO-1234yf as a refrigerant

Proceedings of the Institution of Mechanical Engineers, Part E:

Ramakrishnan

et al. 2019

In this work, the experimental investigation on the performance and exergy analysis of mobile air conditioning system with suction line heat exchanger using environmental friendly HFO-1234yf was carried out under varied evaporator air flow rates. The performance was compared with existing HFC-134a results. The performance analysis showed that the cooling capacity and the coefficient of performance of the system with HFO-1234yf were lower than that of the HFC-134a by upto 2–11%. The power consumption and the volumetric efficiency of the compressor with HFO-1234yf were found to be 14.02% and 11.2% higher than that of HFC-134a. From the exergy analysis, it was observed that the major exergy destruction occurred in the compressor, followed by the condenser, evaporator, thermostatic expansion valve, and suction line heat exchanger for both refrigerants. The exergy efficiency of the system with HFO-1234yf was 2.4–12.6% lower than that of HFC-134a. From this study, it was observed that the losses experienced in the compressor, thermostatic expansion valve and evaporator lead to poor performance with HFO-1234yf.

“…Exergy destructions for the main components of the VCR cycle are calculated based on the methods followed by Dincer and Kanoglu 19 and Prabakaran and Lal. 30…”

Section: Cop ¼ Q Evap W Ele ð1þmentioning

confidence: 99%

“… where E·x is the exergy destruction rate, and ɛ·in-ɛ·out is the rate of total exergy shifted by means of heat, work, and mass interfaces in the process. The exergy destruction rate is determined by the entropy generation in a process using equation (6) 19,30 …”

Section: Data Reductionmentioning

confidence: 99%

Thermal analysis on optimizing the capillary tube length of a milk chiller using DC compressor operated with HFC-134a and environment-friendly HC-600a refrigerants

Proceedings of the Institution of Mechanical Engineers, Part E:

Lal

2019

In this work, the thermal analysis on optimizing the capillary tube lengths of a dual circuit refrigeration system was carried out experimentally. Two refrigeration circuits were individually operated using two DC powered compressors (HFC-134a and HC-600a) instead of conventional AC powered compressors. The capillary tube optimization was done to maximize the coefficient of performance and exergy efficiency. From the results, it was found that the power consumption and the refrigerant mass flow rate decreases with the increase of capillary tube length for both the HFC-134a and HC-600a circuits, while the refrigeration capacity and coefficient of performance increased up to the capillary tube length of 4.57 m and then decreased. The maximum refrigeration capacity, ice formed, power consumption, and coefficient of performance experienced in the HC-600a circuit were 9.65%, 19.03%, 3.53%, and 7.34% lower than those of the HFC-134a circuit at the optimum capillary tube length. It was also found that at the optimum capillary length, the COP was maximum for the HFC-134a circuit while the exergy efficiency was maximum for the HC-600a circuit. The exergy efficiency of the HC-600a circuit was 11.13% higher than that of the HFC-134a circuit. At the optimum capillary tube length, the total equivalent warming impact values of the HFC-134a and HC-600a circuits were 961.13 kg CO2-eq and 785.77 kg CO2-eq, respectively.