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In this study, heat and moisture transfer model of an enthalpy exchanger is proposed. With separately measured sorption constant and diffusion coefficient, the model predicts the heat and moisture transfer effectiveness of an enthalpy exchanger. Two sample enthalpy exchangers were tested at a KS condition to verify the model. The model predicts the heat transfer effectiveness within 4%, and the moisture transfer effectiveness within 10%. Pressure drop is predicted within 6%. The spacer fin efficiency for heat transfer was 0.11 to 0.13. The fin efficiency for moisture transfer, however, was negligibly small. For heat transfer, the conduction resistance to total thermal resistance was less than 1%. For moisture transfer, however, membrane resistance was dominant to convective moisture transfer resistance.

A variable speed refrigeration system was designed to supply chilled liquid for cooling high-power electronic devices to maintain the temperature at an acceptable level. Fin-plate heat exchangers were adopted to save space. The paper presents the simulation of the refrigeration system to study its steady performance. The simulation model was developed by using a detailed thermodynamic model and containing a series of heat transfer correlations for specific parameters. The cooling capacity of the refrigeration system under different working conditions is investigated. The simulation results keep in agreement with experimental data. The cooling capacity increases with the rise of cooled oil inlet temperature. Besides, condenser cooling liquid inlet temperature affects the cooling capacity greatly. The cooling capacity and the coefficient of performance (COP) of the system under different motor speeds are studied subsequently. The simulation results have been validated by experiments. The mean relative error of the cooling capacity and the COP between simulation results and experimental data is 12.6% and 4.8%, respectively. The results can be used to develop control strategy for regulating refrigeration flow rate to offer adequate cooling capacity and supply cooled oil of constant temperature.

Ammonia-absorption refrigeration units (AARUS) can supply subfreezing refrigeration for many industrial applications. Such units are usually driven by waste heat or renewable energy at relatively low temperatures. The performance of the chiller is highly dependent on the temperatures of the driving heat, the chilling load, and the cooling water. In this paper, the performance of an advanced industrial-scale ammonia-absorption unit is modeled over a representative operating range. The performance is then characterized by a set of simple equations incorporating the three external temperatures. This simple model helps to evaluate potential applications, predict performance, and perform initial optimization. Case studies are presented highlighting the application of the model.

This paper presents the development of a numerical, iterative and nonisentropic model for the thermodynamic processes of a reciprocating compressor of a refrigeration system operating at steady state. The mathematical model was implemented using the scientific software Engineering Equation Solver (EES) and it is based on the application of the energy equations in four regions of the compressor: inlet duct and chambers of pre-compression, compression, and post-compression. The model was validated with experimental data collected from an open-drive reciprocating compressor, operating with the refrigerant R-134a at different suction and discharge pressures and with different compressor rotational speeds. Model validation was made comparing the values of the mass flow rate and the discharge temperature of the compressor generated by the model with their corresponding experimental values for 33 experimental tests, the mean relative difference was $-$0.2% for the discharge temperature and 2.9% for mass flow rate. In this validation, the output variables of the model were calculated considering the uncertainties from the input variables. The theoretical mean standard uncertainty is 2% for discharge temperature and 6% for mass flow rate. An analysis of the capacitive and thermal performance of the compressor was made using the model, which demonstrates a decrease in the capacitive and thermal efficiencies for increasing the pressure ratio or clearance volume.

Implementation of trans-regional water transfer is facing a series of problems. First of all, scheduling and management of water resources involves how to determination of water resources quantity and how to realize the maximum benefit of water resources. On the one hand, water transfer cannot influence the use of water and public interests in water division area. On the other hand, water diversion should meet demand of intake area without causing waste of water resources, so as to improve the comprehensive benefit of cross-regional water transfer project. This paper studies the calculation model of harmonious water price, and how to use AHP to confirm the weight of the weight coefficient of water diversion area and the intake area. By analyzing the composition of the water price of Dong-shen water supply project, according to the harmony coefficient, decision-making price of water and affordable price of HK people, reasonable water price has been calculated.

Arable lands are a nation's and a region's very base of food security. It is therefore hardly surprising that the model for computing arable land pressure index has drawn increasing attentions in recent years. This paper elucidates the two major issues associated with the existing arable pressure index model, i.e. the difficulty in the computation of multiple-cropping index and issue of the steep sloping cropland either greater than or equal to 25° in the arable land base in a given mountainous area, and based on which, presents and makes a general analysis of the two improved models suggested by some Chinese scholars in recent years. An empirical comparative analysis is conducted by taking Yunnan, a mountainous border province in southwest China, as an illustrative example, and finally, concludes that the Improved Model I has successfully solved the difficulty in the computation of multiple-cropping index with the existing model. The Improved Model II is able to provide a real solution that is more suitable, feasible, and almost universal for most mountainous areas, as slopes steeper than 25° are completely excluded from the arable land base of a given mountainous area in this model. The computations show that the Improved Model II can produce a much more objective result, especially for mountainous areas where slopes steeper than 25° account for a large percentage of arable lands therein.

In recent years, in order to relieve the pressure of petroleum crisis and environment deterioration, the global transportation sector began to vigorously support the development of new energy cars, especially Electric Vehicles (EVs). Charging stations as EVs infrastructures, provide energy supply services for vehicles. They become one of the key factors restricting the development of EVs. Therefore, the construction of charging stations, especially the early stage of the site selection, got high attention by researchers from all over the world. In this paper, based on the background, research the plant location problem of EVs. Through combined with the specific situation of China, we put forward a new planning and site selection model based on gas station network. And then a numerical experiment to verify the effectiveness of the model. It provides certain reference basis for the actual cases.