Search

In this paper, irreversibility analysis of an ejector refrigeration system (ERS) is carried out using modified Gouy-Stodola formulation that incorporates the use of an effective temperature unlike the surrounding temperature employed in classical Gouy-Stodola equation for the irreversibility determination. The components of any system do not transfer heat at surrounding temperature all the times and thus some error is involved in the analysis, as the conventional equation calculates irreversibility using the surrounding temperature. The use of effective temperature provides more accurate measurement of exergy destruction. R1234ze is the refrigerant in this study due to its low Global Warming Potential (GWP) and zero Ozone Depletion Potential (ODP) and is compared with its counterpart R134a. The study is conducted for a fixed 10 kW cooling system. The coefficient of performance (COP) is found to increase by 15.93% and 11.68% for R1234ze and R134a respectively with the change in generator temperature from 91℃ to 99℃. However, the drop in COP is 52.38% and 58.54% for R1234ze and R134a respectively with increase in condenser temperature from 32℃ to 40℃. It shows that R1234ze performs better than R134a. Due to the highest coefficient of structural bonding (CSB) value in the evaporator, the change in total irreversibility is particularly susceptible to changes in evaporator temperature.

The greenhouse gas emission in atmosphere has been increasing day by day and cooking is one of the primary reasons for this due to the burning of fossile fuels. In the current research article, the thermal performance of solar pressurize cooker has been investigated experimentally. It is an indirect type of cooker setup in which a pressurized cooker and solar collector are placed apart. Heat transfer fluid is used to transmit heat from a conical receiver to a cooking pot. The cooking potential of the cooker is observed by cooking different edible food at different cooking loads. The cooking is done by circulating heat transfer fluid. Also, energy and exergy analysis have been done for the pressurized cooking used for heating 2 liter of water. The water in cooking pot took 65 minutes to reach the temperature of 100℃. The maximum energy and exergy efficiency values are found to be 32.62% and 22.11%, respectively, whereas, the average energy and exergy efficiency are determined to be 10.58% and 7.08%, respectively. The temperature of heat transfer fluid reached upto 170℃, and the maximum temperature in cooking pot achieved to 151℃. It is observed that cooking system can cook different kinds of edible foods of different cooking load. The system is able to cook at medium temperatures for almost six hours. The system has been successfully tested with a maximum cooking load of 3 litres. The system is long-lasting and requires minimal maintenance.

In order to assess the ejector cooling cycle performance and the ejector dimensions, a one-dimensional ejector model is proposed in this paper. The velocity and pressure inside the ejector are examined using thermodynamic governing equations for the eco-friendly working fluids, presuming them as ideal gases. Using conservation of mass, momentum, and energy, the system performance is evaluated. The coefficient of performance (COP) describes the cycle performance, while ejector performance is evaluated in terms of entrainment ratio (ER), mixing area ratio ARMix and primary nozzle area ratio ARNozzle. The performance of the cycle is found to improve with the increase in generator and evaporator temperatures, and the decrease in condenser temperature. The area ratios also followed the same trend with the variation of these parameters. At the designed cooling load of 1 kW, the coefficient of performance is found to be 0.182 for R1234ze and 0.061 for R1234yf; and the entrainment ratio of the ejector is 0.237 for R1234ze and 0.08 for R1234yf. As the temperature of the evaporator is increased from 0 to 10℃, the COP is found to rise by 41.41% and 35.56% for R1234ze and R1234yf, respectively. The COP is increased by 6.63% and 40.98% for R1234ze and R1234yf, respectively when the degree of superheat in the generator is enhanced from 2℃ to 6℃ at constant 3000kPa generator pressure.