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建立了考虑外部有限速率传热过程和热源间热漏的不可逆半导体固态热离子制冷器模型,基于非平衡热力学和有限时间热力学理论导出了热离子制冷器的制冷率和制冷系数的表达式;对比分析了不可逆热离子制冷器与可逆热离子制冷器的发射电流密度特性、电极温度特性以及制冷系数特性;研究了不可逆系统的制冷率与制冷系数最优性能,得到了制冷率和制冷系数的最优运行区间;通过数值计算,详细讨论了外部传热以及内部导热、热源间热漏损失、热源温度、外加电压、半导体材料势垒等设计参数对热离子装置性能的影响。在总传热面积一定的条件下,进一步优化了高、低温侧换热器的面积分配以获得最佳的制冷率和制冷系数特性。结果表明,由于存在内部和外部的不可逆性,热离子装置的发射电流密度及制冷系数都会明显降低;不可逆半导体固态热离子制冷器的制冷率与制冷系数特性呈扭叶型;合理地选外加电压、势垒等参数,可以使制冷器设计于最大制冷率或最大制冷系数的状态。 相似文献
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基于生态学目标函数对线性唯象律下的三热源热泵进行优化分析,导出热泵的生态学优化性能,并与最大供热率工况进行比较,获得一些重要新结论,它对太阳能热泵、吸收式热泵等一类三热源热泵的优化设计和最佳工况选择等均有指导意义 相似文献
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建立一种不可逆的四温度位吸收式热泵模型,导出其最小传热面积与四热源熵变化率的关系并得到了热力学第二定律的类比表达式,获得了最佳供热率、性能系数和传热面积之间的优化关系,所得结论可为四热源吸收式热泵的优化设计和最佳工况选择提供新的理论途径。 相似文献
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研究存在热阻和回热损失的埃里克森热机的(火用)经济优化性能和生态学优化性能,得到一些新的性能参数,并揭示了(火用)经济优化性能与生态学优化性能间的联系,所得结果具有普遍意义,可为埃里克森热机的研制和优化设计提供些新理论指导. 相似文献
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In this study, a side-by-side test was performed on a glazed and an unglazed collector/regenerator operating under identical environmental conditions. This test procedure differed from previous experiments in that the inlet solution state was maintained constant during the period of testing. Also, for the glazed C/R, local solution film temperatures as well as entrance and exit air dry and wet bulb temperatures were measured. With the use of experimental data, empirical correlations were developed for heat and mass transfer coefficients in terms of Nusselt and Sherwood numbers. These correlations were used in the simulation study to identify important variables affecting the performance of each collector/regenerator. The performance of the glazed collector/regenerator was considerably affected by solution flow rate, solar irradiation, ambient temperature, solution temperature and concentration at the inlet, and glazing height. The evaporation rate for the unglazed collector/regenerator was strongly dependent upon ambient temperature, humidity, wind speed, and solution concentration at the inlet to the collector/regenerator. Generally, it was found that the unglazed C/R performed better than the glazed C/R for the conditions considered in this study. Contrary to previous research, this data showed an increase in evaporation rate as the gap height was decreased from 15 to 7 cm. The glazing, also helped to maintain cleaner absorbent solution and reduced waste due to rain. © 1997 by John Wiley & Sons, Ltd. 相似文献
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