Experimental Investigation Of Heat Transfer Enhancement In The Copper Wire-Bonded Flat Heat Pipe Using Nanofluids

An experimental investigation of thermal characteristics of two flat heat pipes is presented in this paper. The working fluid is nanofluid. The effects on thermal performance of pressure,concentration,critical heat flux will be analyzed.The result is obtained in terms of axial temperature distribution, axial temperature difference, heat transfer capacity, total heat resistance, coefficients of evaporator section and condenser section, etc. Experimental results in the experiment of copper wire-bonded flat heat pipe indicate that:Firstly, compared with ethyl alcohol, the coefficients of heat transfer and the maximum heat flux of deionized water in the copper wire-bonded flat heat pipe is much better. Compared with ethyl alcohol and deionized water, nanoparticle suspension could greatly enhance the coefficients of heat transfer and improve the maximum heat flux in the heat pipe.Secondly, the thermal performance of copper wire-bonded flat heat pipe increased with increasing of the particle concentration in water and then decreased apparently which indicated that an optimal particle concentration in water existed.Thirdly, compared with Cu nanoparticle of 50nm suspension and CuO nanoparticle of 50nm suspension, Cu nanoparticle of 20nm suspension could greatly enhance the coefficients of heat transfer and improve the maximum heat flux in the heat pipe. Fourthly, Adding Cu nanoparticle of 20nm into the ethyl alcohol could also improve the performance of heat transfer and the maximum heat flux in the copper wire-bonded flat heat pipe, which is similar to the performance of nanoparticle-water suspension.When the experiment of copper wire-bonded flat heat pipe had been done, a mesh screen was put on the series of parallel copper wires and the experimental investigation of thermal characteristics of the copper wire-bonded and mesh screen flat heat pipe would be taken on. The mesh screen is stainless steel and mesh number of 300.Experimental results in the experiment of copper wire-bonded and mesh screen flat heat pipe indicate that:Compared with deionized water, Adding Cu nanoparticle of 20nm into the deionized water could also improve the performance of heat transfer and the maximum heat flux in the copper wire-bonded and mesh screen flat heat pipe, which is similar to the performance of the copper wire-bonded flat heat pipe. An optimal particle concentration in water also existed, which is also 1.0wt%.Compared the thermal performances of the copper wire-bonded flat heat pipe with the copper wire-bonded and mesh screen flat heat pipe. The temperature distribution on surface of the latter is more uniform. The total heat resistance of the latter is lower. The maximum heat flux of the latter is higher.Experiment showed that the nano-fluid could greatly increase the heat transfer coefficient and critical heat flux of the two flat heat pipes. Nano-fluid was a very suitable working fluid employed in the flat heat pipe. It is a potential new kind of working fluid to enhance the heat transfer characteristics of heat pipe with high heat flux.