طراحي و ساخت مبدل حرارتي مايع - گاز با استفاده از لوله هاي گرمايي

Design Experience with Liquid-to-Gas Heat Exchanger Using Finned Heat Pipes

Heat pipes are high capacity heat transfer devices. Therefore, many studies have been carried out on their theory and application in Liquid-Gas heat exchangers and radiators. In the present study, a heat exchanger composed of 18 thermosyphones (heat pipes • without wicks) arranged in two rows with staggered configuration was constructed. • Heat was absorbed by lower part of the tube from hot water and removed from upper part of the tube by air stream. Analysis showed that the boiling limit is the lowest limit. Since the capacity of each thermosyphone is lower than this limit, it is assured that the designed thermosyphones operate securely at the design condition. Calculations showed that they are capable of transferring 1908 Watts heat from a hot water with 80 degree centigrade temperature and 6 liters per minute flow. Experimental results approved a capacity of 1730 watts. Comparison of the two mentioned values indicates the satisfactory design and construction. Theoretical and experimental values of heat transfer coefficient of inside and outside of the condensing part of the tube are in good agreement. The inside heat transfer coefficient of the used heat pipes was 7900 w/m2.K while this value is 230 for a similar metallic tube.