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Refrigeration Cycles
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
The simple vapor compression refrigeration system is the most prominent refrigeration system for most of the refrigeration needs, since it is simple in construction, is less expensive, and requires less maintenance. Despite these advantages, it has some drawbacks that it is not suitable for large industrial refrigeration units in which simplicity is not the criterion but the efficiency and higher ranges of temperature are more important. It is therefore inevitable to improve the efficiency of the existing simple vapor compression refrigeration, so that they can be used advantageously for a wide range of applications. There are different alternative ways to accomplish this task. Using multistage compression is one such alternative, and operating two cycles in series, called cascading, is another approach. Apart from these methods, liquefaction of gases also proves to be a viable option.
Numerical Modeling and Simulation
Published in Yogesh Jaluria, Design and Optimization of Thermal Systems, 2019
The first step in the mathematical and numerical modeling of a thermal system is to focus on the various parts or components that make up the system. In many cases, the choice of individual components is obvious. For instance, in a vapor compression refrigeration system, the compressor, the condenser, the evaporator, and the throttling value may be taken as the components of the system (see Figure 4.19). Each component here may be considered as a separate entity, in terms of the thermodynamic process undergone by the refrigerant and geometry, design, and location of the component. Similar subdivisions are employed in many thermodynamic systems such as those in energy generation, heating, cooling, and transportation. The components are chosen so that these are relatively self-contained and independent in order to facilitate the modeling. However, all such components must ultimately be linked to each other through energy, material, and momentum transport. For instance, in a refrigeration system, the refrigerant flows from one component to the other, conveying the energy stored in the fluid, as shown in Figure 1.8. In each component, energy exchanges occur, leading to the resulting thermodynamic state of the fluid at the exit of the component.
Case Studies of Parametric Accelerated Life Testing
Published in Seong-woo Woo, Design of Mechanical Systems Based on Statistics, 2021
A reciprocating compressor is a positive-displacement machine that uses a piston to compress a gas and deliver it at high pressure through a slider-crank mechanism. A refrigerator system, which operates using the basic principles of thermodynamics, consists of a compressor, a condenser, a capillary tube, and an evaporator. The vapor compression refrigeration cycle receives work from the compressor and transfers heat from the evaporator to the condenser. The main function of the refrigerator is to provide cold air from the evaporator to the freezer and refrigerator compartments. Consequently, it keeps the stored food fresh.
Enhancement of Performance and Energy Efficiency of Air Conditioning System Using Evaporatively Cooled Condensers
Published in Heat Transfer Engineering, 2019
Theodore A. Ndukaife, A. G. Agwu Nnanna
This relationship is investigated to determine the effect of the drop in refrigerant condensing temperature on the COP. Results obtained show that a 1°C drop in condensing temperature causes a 4% increase in COP. This information is necessary in predicting the performance of such systems in any climate, and shows the effect of condensing temperature on the COP. As shown in Figure 10, as the drop in refrigerant condensing temperature increased, the percentage change in COP also increased. The drop in refrigerant condensing temperature is obtained from the difference between the condensing temperatures with and without the application of evaporative cooling to the system. This shows that exploiting the condenser for evaporative cooling will significantly increase the efficiency of an air conditioning system or any vapor compression refrigeration unit.
Co- and tri-generation system based on absorption refrigeration cysle: a review
Published in International Journal of Green Energy, 2020
Mingzhang Pan, Yanmei Huang, Yan Zhu, Dongwu Liang, Youcai Liang, Guopeng Yu
Traditional vapor compression refrigeration system needs to be driven by high grade energy, and the refrigerants used in it will lead to ozone layer depletion and green house effects. On the contrary, absorption refrigeration system (ARS) is heat-driven and less work input is required to pump the liquid (Kaynakli and Kilic 2007; Manzela et al. 2010). Industrial exhaust gas, geothermal energy, solar energy, and so on can be the heat source of the absorption refrigeration system. Moreover, absorption refrigeration system does not use any chlorofluorocarbon or hydrofluorocarbon refrigerants as the working fluids, so causing zero or minimum ozone depletion (Misra, Sahoo, and Gupta 2006).
Multi-objective optimization of a Stirling cooler using particle swarm optimization algorithm
Published in Science and Technology for the Built Environment, 2022
Lifeng Wang, Pu Zheng, Yuzhe Ji, Xi Chen
The refrigeration and air-conditioning apparatuses are widely used around the world, and most of the refrigeration requirements rely on the vapor compression refrigeration system. However, the refrigerants in the vapor compression refrigeration system have a negative impact on the ozone layer and global warming issues (Wu et al. 2021). It is necessary to seek substitutes for the current vapor compression refrigeration system.