Abstract:In this study, cases of single-stage and multi-stage compression have been compared and contrasted through various angles while concentrating on refrigeration systems with 600 kW cooling capacity and working with ammonia. For five different numbers of stages, power consumption, costs of investment, operation and maintenance (O and M), COP and 2nd law efficiencies have been calculated. As the amount of stages increase, power consumption decreases. The payback period of the gain from this decrease has been calculated as far as the increasing investment expenditures are concerned. Dimensionless profit factor has been calculated according to each case and presented in the diagram.
The exergoeconomic theory is applied to a two stage vapour compression refrigeration cycle. An exergy-aided cost analysis, taking into account pressure drops and heat gain/loss for all of the components in the refrigeration system as well as the pipe connections, has been made. Exergoeconomic factors, showing whether the monetary expenditures mostly originate from capital investment and Operating and Maintenance (O&M) costs or from exergy destruction and exergy loss, are found and shown in the form of tables. The true cost of the heat drawn from cold room, which is the product of a refrigeration sytem, has been calculated. In this way, it will be possible to reflect the cost of cold room storage to the market price of the goods completely and precisely
In this study, the effects of thermal losses in steam valves for flow have been analyzed. In a set of experiment built to achieve this, pressure and condensate values have been calculated in different temperatures for insulated and non-insulated cases in three different nominal diameter steam valves. The amount of energy lost from the valve surface in the natural convection conditions has been calculated through application and use of principles of heat transfer and fluid mechanics and equations of mass and energy conservation. Thermal loss coefficient change and the amount of the heat transferred from surface in 150°C steam temperature for different steam velocities have been presented in diagrams. Heat losses have been calculated in two different steam velocities in the cases of five different steam temperatures and their diagrams have been arranged
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