An effective thermodynamic transformation analysis method was proposed in this study. According to the phenomenon of exergy consumption always coupling with heat transfer process, the effective thermodynamic temperatures were defined, then the actual power cycle or refrigeration/heat pump cycle was transformed into the equivalent reversible Carnot or reverse Carnot cycles for thermodynamic analysis. The derived effective thermodynamic temperature of the hot reservoir of the equivalent reverse Carnot cycle is the basis of the proposed method. The combined diagram of TR-h and TR-q was adopted for the analysis of the system performance and the exergy consumption, which takes advantage of the visual expression of the heat/work exchange and the enthalpy change, and is convenient for the calculation of the coefficient of performance and exergy consumptions. Take a heat pump water heater with refrigerant of R22 for example, the proposed method was systematically introduced, and the fitting formulas of the effective thermodynamic temperatures were given as demonstration. The results show that the proposed method has advantage and well application foreground in the performance simulation and estimation under the variable working conditions.

Thermoelectric materials are of interest for applications as heat pump and power generators. The performance of a thermoelectric material, the figure of merit, ZT , is measured. The figure of merit is interrelated to the thermal conductivity, electrical conductivity, and Seebeck coefficient. All of these parameters are functions of temperature. The performance of a Bi–Te–Sb–Se thermoelectric material at low temperature was studied experimentally in this work. Based on the experimental results, the relation between various parameters and temperature, and the figure of merit are reported. The conclusions indicate that this thermoelectric material is not suitable for power generation at low temperature, and only an improvement of production technology or the development of a new production method can improve the electrical power generation performance with this method.

A basic model of semiconductor thermoelectric generator is constituted. Based on the steady conduction equation, thermodynamic process has been analyzed. Temperature function, output power and generating efficiency of p and n semiconductor are obtained. The Seebeck coefficient S of a kind of Bi-Te-Sb-Se thermoelectric material at low temperature has been experimentally researched. Based on the experiment, the function between S and T of this material has been expressed. The conclusion indicates that this kind of thermoelectric material is unsuitable for power generation at low temperature, and only the enhancement of production technology or appearance of new production method can improve the electrical power generation performance.

A system utilizing LNG cold energy to generate power output was proposed. This system is combined with a LNG power generation cycle and a thermoelectric generator (TEG), which is also a heat exchanger at the same time. The performance of the system has been analyzed and calculated for different methane concentrations in LNG. The calculation results showed that the energy efficiency of this power generation system is up to 29%.

The cold energy of liquefied natural gas (LNG) is generally wasted when the LNG is extracted for utilization. This paper proposes cryogenic thermoelectric generators to recover this cold energy. The theoretical performance of the generator has been analyzed. An analytical method and numerical method of calculation of the optimum parameters of the generator have been demonstrated.

为了对液化天然气(LNG)的冷能回收利用,对半导体热电材料在低温下的发电性能进行了实验研究,得到了这种热电材料的发电性能随冷端温度变化的关系,并发现在热端温度不变的情况下,冷端温度在特定温度下热电堆的输出电动势达到最大值.运用数值方法理论计算了该热电堆在实验所处条件下的输出电动势,并将计算值与实验值进行了对比.

A basic model of semiconductor thermoelectric generator was constituted. Based on the model, the expression of thermoelectric generators thermal conductivity was derived, which is closely associated with the thermal conductivity of N type semiconductor, P type semiconductor and ceramic plate. Experimental research on the relationship between temperature and thermal conductivity was preceded, and curves about the relationship were plotted. Result indicates that theoretical value is approximate with experimental data.

The relation ship between thermal conductivity and w ater content of tobacco is presented in this paper. The accuracy of the recommen ded formula is checked by experimental data. The calculated results agree very w ell with the experimental data. For leaf tobacco stack, the absolute average dev iation is 1.75%,and the arithmetic average deviation is 0.15%, while for cut tobacco as compared with 2.36% and 0.25%, respectively, for cut tobacco. The for mula can be also used to calculate other porous material.

This paper presents a design scheme of air cooled vertical falling film absorber. A new numerical model was established to calculate the coupling heat and mass transfer during the absorption process in vertical falling film absorber. The changes of liquid film temperature and liquid film concentration with respect to different convection coefficients, showering distances and pipe diameters were described. The results are helpful to the development of air cooling absorber.

In the NaCl–CaCl2 molten salt, a solid agglomerate of Fe2O3 particles is used as a raw material, and a graphite rod is used as an anode. At 800 °C, the composition and morphology of the product obtained by cyclic voltammetry and combined with constant cell pressure electrolysis at different times were analyzed by XRD and SEM to obtain the reduction mechanism of solid Fe2O3. (1) chemical formation of Ca2Fe2O5; (2) Ca2Fe2O5 was electrochemically reduced to metallic iron Ca2Fe2O5 → Fe3O4 → FeO → Fe, and finally electrolyzed for 5 h at a battery voltage of 2.5 V to prepare metal iron with an oxygen content of 1.29%. The electrolysis efficiency was 97.6%. The electrolysis product iron appears as interconnected micron-sized network particles. These studies provide theoretical support for the direct electroreduction of Fe2O3 particles to prepare metallic iron.