Conclusion and Future Research
An experiment has been conducted on loop heat pipe during the present study. Result of the experiment includes the development and evaluation of the performance of LHP at different heat load condition. Numerous tests were performed to study the transient operation of LHP. The current technique provides the opportunity to observe the fluid behavior in the loop. Images taken by the high-speed camera illustrate the startup process as well as behavior of fluid in different component. Understanding of these phenomena will help to improve the efficiency of the loop. The specific goals have been accomplished mentioned in chapter 1. The outcome of the experiment can be concluded as follows
A LHP has been designed and developed with disc shape wick. The main structure of the LHP is constructed from the acrylic plastic and the working fluid is water. LHP was able to handle 100-watt heat load with the total thermal resistance of 0.78
and heat transfer coefficient of 14.114 . The most stable condition was observed for 90-watt heat load. Total thermal resistance for this load is 0.844 and heat transfer coefficient is 8.9 .
Temperature oscillation was observed in the loop heat pipe during startup and at low heat load. Chaotic behavior of the temperature has been noticed for 20 and 30 watt. The reason for the huge oscillation is instability of the meniscus.
A high-speed camera was used to visualize the operational behavior of the LHP. Four main stages of the startup process have been analyzed with the help of visualization process. The reasons for temperature oscillation in the evaporator and in the condenser were confirmed through the visualization process. Images taken by the high-speed
camera verify heat leakage to the compensation chamber, existence of the two-phase flow in the condenser and development of bubble in the compensation chamber at the high heat load.
The manufactured LHP can operate satisfactorily at relatively high heat load. The system is compact and can be used for the cooling of electronic devices.
Though the present study provides an insight into the operational characteristic of LHP, future research needs to be done for improvement in efficiency. Recommendation for the future research is sighted below
Measurement of pressure at the different components of LHP will give insight into pressure drop along the system.
Decrease in the working temperature of the system is possible by using various working fluids. Working fluid like ammonia, ethanol can be used for low operating temperature. Measurement of the flow rate and vapor quality
Investigation of two-phase instability in condenser can improve the condensation process. Development of a CFD code will help to understand the transient model of LHP more
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