Discuss The Advantages And Disadvantages Of Carbon Dioxide As An Alternative To Hydroflorocarbon

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Here we consider a recent article by Fukuta1 which discusses the usage of carbon dioxide (CO2) as an alternative to hydroflorocarbon (HFC) in refrigeration and heat pump cycles. CO2, a natural refrigerant, is non-toxic, non-flammable, and has good thermodynamic properties. The only disadvantage of using CO2 as a refrigerant is that the coefficient of performance of CO2 cycles is lower than HFC cycles, especially if the surrounding’s temperature is high. Therefore, an expander must be used in order to improve the performance of the CO2 cycles. The expander operates under a transcritical condition, where the CO2 changes from supercritical to a two-phase condition. This expansion process operates using a piston expander, the expansion chamber, and a valve that is used to allow the flow of CO2 into the expansion chamber. The expansion chamber has two glass windows on opposite sides so that the expansion process can be clearly observed by using either transmitted light or reflected light. The first step in this process is the charging of the liquid CO2 from the CO2 cylinder to another tank used for controlling the pressure. This tank works by using an electric heater, which is wrapped around the tank. As a result the temperature will increase, and therefore, CO2 is changed to a supercritical state. The second step is opening the valve and allowing the flow of CO2 into the expansion chamber. One of the most important factors in this expansion process is the heat transfer, since

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