| Summary: | 碩士 === 南台科技大學 === 機械工程系 === 101 === This study investigates influences of spray nozzle cone angle on spray heat transfer performance of an internal shell-and-tube spray evaporator with triangular-configuration pipe group, and compares heat transfer performance of spray nozzle cone angle with the calculated optimal spray coverage rate. It is found that parameters affecting heat transfer performance of spray-type evaporator include mass flow rate during spray, spray nozzle form (including pore size and cone angle), spacing, spray incidence angle, subcooling of sprayed liquid, flow field, and flow rate of heating, tec. This study focuses on form of spray nozzle (cone angle), adopts theoretical inference and then finds a cone angle of 10° obtains the best spray coverage rate. Heat transfer performance comparisons with 0°, 30° and 45° are also done: when cone angle of spray nozzle is 10°, pipe group can fully cover refrigerant. Moreover, under the same mass flow rate, 10° cone angle has a heat transfer performance about 48% higher than 45° due to a smaller cone angle, no outward diffusion of post-spray droplets, a stronger force of collision and an even spray of refrigerant onto all pipe groups after calculation. When cone angle is 0°, despite the strongest spraying force and no outward diffusion of droplet, heat transfer performance is just suboptimal as refrigerants are not evenly sprayed onto all pipe groups. Under the cone angle of 30° or 45°, in spite of even spray of refrigerant onto pipe group, outward diffusion of droplet results in weak spraying power and thus poor heat transfer performance.
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