Study of a cooling system for draught drinks

This is a brief review written by us of above mention article taken from sciencedirect.com 

Introduction


Draught drinks cooling system can be found in bars, restaurants and clubs etc which work 24 hours a day and 7 days a week. The basic draught drinks cooling system consist of two sub systems one is refrigeration subsystem and other is drink subsystem. The refrigeration subsystem consist of compressor, condenser, condenser fan, filter, expansion valve( capillary tube), internal heat exchanger and evaporator while drink subsystem consist of beverage coil,  column and tap. Other than this system has a tank having water in it. Evaporator and beverage coil both are also placed in the tank.




Working


During working evaporator absorb heat from water and drop its temperature to 0 degree C this water absorb heat from the beverage in beverage coil and drops its temperature to 3 degree C. Beverage in the column and tap is exposed to ambient temperature where its temperature can drop so to maintain a constant temperature water from the tank is circulated in the column and tap section with the help of a pump. In ideal working compressor work for 5 min and them switch of 23 min. In this 23 min ice in the tank melt and then in 5 min compressor restore it so the one cycle of refrigeration system is of 28 min. this can vary from on application to other like in small restaurant in peek consumption it is 30 min and in bars it is up to 73 min.






Experimental setup and Calculations

To measure the temperature and pressure, sensors are placed before and after the compressor, condenser, filter, expansion valve, internal heat exchanger and evaporator. When system start working we got the temperature and pressure readings and base on this information we made our calculation. When work done by compressor is known then we can find out mass flow rate and then with the help of the formula 
and steam table we can find the heat absorb or rejected by the condenser and expansion valve. Then with help of 2nd law of thermodynamic we can find the heat absorbed by the evaporator. Now we can find out the overall coefficient of performance of the refrigeration system.




In beverage cooling system there are three places from where ice can gain heat one is the outer atmosphere second is the beverage itself and the third is stirrer and pump installed inside the tank. Maximum heat absorb by the ice is when there is maximum consumption of beverage which depends upon the designing limitation of the machine. Power needed to cool down the beverage when there is maximum consumption is

Heat gain by the ice from the outer atmosphere came through lateral walls, bottom wall and top wall. Resistance given by each wall in heat flow is depending upon its thickness, area and thermal conductivity.


 Improvements needed

There are some improvements needed for this system like replacement of low efficient internal heat exchanger (having only 15% efficiency) by more efficient heat exchanger. System work 24 hours a day but when bar is closed there is consumption of energy for 5 min after every 23 min with no profit or beverage output solution is stop the machine when bar is closed but the problem is when bar is reopen system will take time to restore ice in tank. After experiments it is concluded that a real time clock must be integrated with the system so that sensor start the compressor time before the bar is open.


Conclusion

In this analysis of a cooling system designed for the cooling of the beverage drinks we have used pressure and temperature sensors and EES software for simulation and after many laboratory test we find that the COP of the refrigeration system was good about 3.14 but for the aver all system it was very low about 9.57E-2 which need to be improve. We have suggested the use of more efficient components as well as introducing a new real clock subsystem in the system to save energy.


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