Hassan Shokouhmand; Mohammad Ali Nazari; Babak Ghaem Panah; Mohammad Reza Aligoodarzi
Abstract
In this paper the effect of site conditions, which are Altitude, Temperature and Relative Humidity and also Heat Dissipation Capacity are investigated on the optimized design of natural draft dry cooling towers with specific kind of heat exchangers, known as Forgo T60 type. A genetic algorithm program ...
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In this paper the effect of site conditions, which are Altitude, Temperature and Relative Humidity and also Heat Dissipation Capacity are investigated on the optimized design of natural draft dry cooling towers with specific kind of heat exchangers, known as Forgo T60 type. A genetic algorithm program has been developed for optimized design of these cooling towers. Objective function includes both cost and performance of the tower. The optimized dimensions of the tower, the number of heat exchangers and mass flow rate of water and air are the results of this optimization program. The results show it is possible to find the variation of the optimized value of each design variable versus the variations of the site conditions and heat dissipation capacity. Also finding an optimum for all design parameters for any site condition is possible; however it is very dependent on how exact the cost analysis is.
Hossein Shokouhmand; Hafez Bahrami
Abstract
In this study an analytical model for open loop pulsating heat pipes (PHPs) is presented. The model predicts the effect of different parameters such as evaporator temperature, length of evaporator, filling ratio, number of turn and tube diameter on PHP's performance.
The governing equations in two phase ...
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In this study an analytical model for open loop pulsating heat pipes (PHPs) is presented. The model predicts the effect of different parameters such as evaporator temperature, length of evaporator, filling ratio, number of turn and tube diameter on PHP's performance.
The governing equations in two phase flow including mass, momentum and energy equations are solved for both one dimensional liquid slugs and lumped vapor plugs numerically. The model includes the thin film layer concept which contributes to heat transfer in evaporator and condenser section. A proper model is also investigated to describe the steady oscillatory behavior of device. The results show that this model predicts well the oscillatory behavior of the phenomena. The obtained results are in good agreement with available data and can be properly used for predicting the trend of effective parameters on PHP's performance. It is found that sensible heat transfer has extremely more important role in increasing total heat transfer of PHP . The thermal resistance decreases due to increasing of the latent heat transfer. It can be seen that increasing of the evaporator temperature, while the temperature of the condenser is constant,will increase the total evacuated heat by PHP in specific filling ratio limits. The results show that the PHP's performance increases when the tube diameter increases. In this case, by using a specific non-dimensionalized model, a unique curve for arbitrary number of turn and FR can be obtained. Also it is found that PHP's performance reaches its maximum at filling ratio around 0.6 for different tube diameters.
