In order to guide the application of thermostat dehumidifier products, a performance test device based on air enthalpy contrast method of wind tunnel was designed, the hardware technical requirement and software function are introduced.Byte sting the KFRS-20ZM/AS dehumidifier, the relationship between the amount of desiccant and heat transfer, the amount of unit power and the input power are analyzed, finally the reliability of the test device is verified from the performance test results.

The charging process of Phase Change Material (PCM) packaged in a cylindrical container that melts by absorbing the heat with the Heat Pipe (HP) is simulated in the paper. A two-dimensional physical model is built to couple with the problem that the heat transmission of HP with PCM. An enthalpy model and VOF method is separately introduced to couple with the melting of PCM, the evaporation and the condensation in HP. The numerical simulation reveals that the temperature of the evaporation section rises faster than the condensation section at the beginning and the gap decreases as the continuum flow is established in the entire HP. The PCM temperature distribution is closely related to the flow in the HP. The melting time of the PCM meets the demands of the Solar Dynamic Space Power System (SDPSS). The work in this paper lays a good foundation for further research on the character of the heat transfer of the HP receiver integrated with High-Temperature Latent Thermal Energy Storage (HTLHTES).

The heat pipe (HP) receiver with integrated latent heat thermal energy storage (LHTES) is one of the key components of solar dynamic space power system (SDPSS). Therefore, thermodynamic analysis and optimization of SDPSS is significant for improving system efficiency and reducing launch cost. In this paper, a two-dimensional physical model was developed. Meanwhile, we studied further energy and exergy characters during charging process in microgravity environment. The equation of exergy efficiency was deduced by analyzing the relationship between heat flux and mass flow of HP. Through discussing the key parameters to exergy efficiency (length of evaporator (L-e), length of phase change material (PCM) (L), and length of condenser with Stirling engine (L-1)), the optimization of parameters-L-e = 0.36 m, L = 0.41 m and L-1 = 0.43 m-were obtained by genetic algorithm when exergy efficiency reaches the maximum value of 0.97585. The results provide theoretical guidance for structure design and applications of SDPSS. (C) 2017 Elsevier Ltd. All rights reserved.

The heat pipe receiver with integrated high temperature latent thermal energy storage is one of the key components of Solar Dynamic Space Power System (SDPSS), among which the evaporation and condensation is the main heat transfer mode, a very complicated two-phase flow. However, research on the two-phase flow and heat transfer characteristics is an effective way to improve the system efficiency and reduce the system mass. So a two-dimensional physical model was built and the volume of fluid (VOF) technique was used to model the interaction between the two phases. The UDF (Users Define Function) was introduced to handle the mass source terms. In the study, the relationship between superheat, subcooling and wall heat flux were investigated. In addition, the flow pattern of bubbles in the tube was analyzed. Compared with the churn bubbles flow, the heat transfer coefficient of the bubbles flow was much higher. Bubble departure diameter increased as surface subcooling increased. The work in this paper lays a good foundation for the further research on the heat transfer characteristics of heat pipe receiver with integrated high temperature latent thermal energy storage.

In this paper, a mathematical model for the overall exergy efficiency of combined charging discharging processes of three phase change materials (PCMs) named PCM1, PCM2, PCM3 and different heat transfer fluid (HTF, the solar field HTF and thermal energy storage (TES) system HTF are different) has been developed. The model takes into consideration the effects of inlet temperatures and the number of heat transfer units (NTUs) of the solar field HTF and the TES system HTF on the maximum overall exergy efficiency and the optimum melting temperatures of PCM1, PCM2 and PCM3. The analysis is based on a lumped model for the PCMs which assumes that a PCM is a thermal reservoir with a constant temperature of its melting point and a distributed model for the solar field HTF and the TES system HTF which assume that their temperatures vary in their flow path. The results show that the maximum overall exergy efficiency can be improved by increasing the NTUs of either the solar field HTF or the TES system HTF which is not more than 5. It is found that, for the TES system HTF, increasing its inlet temperature can increase the maximum overall exergy efficiency, however, for the solar field HTF, only when the NTUs of the solar field HTF and the TES system HTF are both more than 2, increasing its inlet temperature can increase the maximum overall exergy efficiency. It is also found that, compared to increasing the NTUs of the TES system HTF, increasing the NTUs of the solar field HTF is more efficient in improving the maximum overall exergy efficiency. Considering actual application of solar thermal power, we suggest that inlet temperature ranges of the solar field HTF and the TES system HTF should be 800-1200 K and 350-400 K, respectively, and the ranges of the NTUs of PCM1, PCM2 and PCM3 should be 4-5, correspond to the ranges of T-m1.opt, T-m2.opt and T-m3.opt are 750-850 K, 550-600 K, 450-500 K, respectively. The present analysis provides theoretical guidance for application of three PCMs storage system for solar thermal power. (C) 2015 Elsevier Ltd. All rights reserved.

In this paper, a mathematical model of shell-and-tube latent heat thermal energy storage (LUTES) unit of two-dimension of three phase change materials (PCMs) named PCM1, PCM2 and PCM3 with different high melting temperatures (983 K, 823 K and 670 K, respectively) and heat transfer fluid (HTF: air) with flowing resistance and viscous dissipation based on the enthalpy method has been developed. Instantaneous solid-liquid interface positions and liquid fractions of PCMs as well as the effects of inlet temperatures of the air and lengths of the shell-and-tube LHTES unit on melting times of PCMs were numerically analyzed. The results show that melting rates of PCM3 are the fastest and that of PCM1 are the slowest both x, r directions. It is also found that the melting times of PCM1, PCM2 and PCM3 decrease with increase in inlet temperatures of the air. Moreover, with increase in inlet temperatures of the air, decreasing degree of their melting times are different, decreasing degree of the melting time of PCM1 is the biggest and that of PCM3 is the smallest. Considering actual application of solar thermal power, we suggest that the optimum lengths are L-1 = 250 mm, L-2 = 400 mm, L-3 = 550 mm (L = 1200 mm) which corresponds to the same melting times of PCM1, PCM2 and PCM3 are about 3230 s and inlet temperature of the air is about 1200 K. The present analysis provides theoretical guidance for designing optimization of the shell-and-tube LHTES unit with three PCMs for solar thermal power. (C) 2013 Elsevier Ltd. All rights reserved.

A mathematical model for the overall exergetic efficiency of two phase change materials named PCM1 and PCM2 storage system with a concentrating collector for solar thermal power based on finite-time thermodynamics is developed. The model takes into consideration the effects of melting temperatures and number of heat transfer unit of PCM1 and PCM2 on the overall exergetic efficiency. The analysis is based on a lumped model for the PCMs which assumes that a PCM is a thermal reservoir with a constant temperature of its melting point and a distributed model for the air which assumes that the temperature of the air varies in its flow path. The results show that the overall exergetic efficiency can be improved by 19.0–53.8% using two PCMs compared with a single PCM. It is found that melting temperatures of PCM1 and PCM2 have different influences on the overall exergetic efficiency, and the overall exergetic efficiency decreases with increasing the melting temperature of PCM1, increases with increasing the melting temperature of PCM2. It is also found that for PCM1, increasing its number of heat transfer unit can increase the overall exergetic efficiency, however, for PCM2, only when the melting temperature of PCM1 is less than 1150K and the melting temperature of PCM2 is more than 750K, increasing the number of heat transfer unit of PCM2 can increase the overall exergetic efficiency. Considering actual application of solar thermal power, we suggest that the optimum melting temperature range of PCM1 is 1000–1150K and that of PCM2 is 750–900K. The present analysis provides theoretical guidance for applications of two PCMs storage system for solar thermal power.

A mathematical model for the overall thermal efficiency of the solar-powered high temperature differential dish-Stirling engine with finite-rate heat transfer, regenerative heat losses, conductive thermal bridging losses and finite regeneration processes time is developed. The model takes into consideration the effect of the absorber temperature and the concentrating ratio on the thermal efficiency; radiation and convection heat transfer between the absorber and the working fluid as well as convection heat transfer between the heat sink and the working fluid. The results show that the optimized absorber temperature and concentrating ratio are at about 1100K and 1300, respectively. The thermal efficiency at optimized condition is about 34%, which is not far away from the corresponding Carnot efficiency at about 50%. Hence, the present analysis provides a new theoretical guidance for designing dish collectors and operating the Stirling heat engine system.