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The measurement of the infiltration airflow rates can support the calculation of the infiltration cooling load for the better understanding and optimizing the energy consumption of cold stores. However, the large temperature difference and the intense transient features make it difficult and complex to measure the airflow rates accurately. In this paper, a simple and practical method to measure the transient infiltration airflow rates is developed by using the local air velocity linear fitting. The proposed method is validated by the measurement results of the tracer gas decay method. It is concluded that the proposed method shows a good performance on the transient infiltration airflow rates measurement. The measurement errors are between ±10%. To enhance the application of this method, the layout of the measuring points of the air velocities are analyzed. The results show that, along the vertical layout direction, air velocity measuring points around the neutral level (where the cold and the warm air separate, about the middle height of the door) are not preferred when using this method. What’s more, the calculation of the infiltration cooling load by using this measuring method is also discussed.

The traditional Air Source Heat Pump (ASHP) for Electric Vehicles (EVs) has many limits in cold region because of poor heating performance and operating safety in low ambient temperature, which can be solved by the ASHP with refrigerant injection. A test bench that can be switched between a traditional ASHP system and a refrigerant injection ASHP system for EVs in the cold region is developed in this study. Compressors applied in the test bench are refitted with different injection portholes from the regular electric scroll compressor to analyze the influence of porthole shape on the system performance. The experimental results show that the heating capacity of refrigerant injection ASHP system is raised up by 28.6% compared with the traditional system. The larger injection porthole helps to increase the heating capacity when in-car inlet air temperature is higher, and the effect of injection porthole shapes to injection process and refrigerant cycle is also analyzed. The research will contribute to the application of refrigerant injection technology in EVs.

Free cooling based on thermosyphon is a promising technology for energy-saving in data centers. Integrated system of mechanical refrigeration and thermosyphon does not need auxiliary refrigeration system, therefore it is an ideal way of free cooling based on thermosyphon. To study its free cooling performance and potential, it is built that a distributed-parameter model of the thermosyphon mode in an integrated system of mechanical refrigeration and thermosyphon and validated by experimental data. The simulation results show that the cooling capacity and circulation flow rate increase with the increase of height difference mainly due to higher driving force of gravity, while the increase is little when the height difference is higher than 0.5 m. The cooling capacity and circulation flow rate decrease with the increase of connection pipe length due to higher flow resistance, therefore the connection pipe should be as short as possible. The cooling capacity increases rapidly with the temperature difference and reaches 5.3 kW when the temperature difference is 15 °C, with an EER of 14.3. Also with the performance model and weather data of China, annual free cooling potential in China and corresponding energy-saving and economic benefits are analyzed. For the studied cities in China except those in the hot summer & warm winter zone, the free cooling percentages are approximately 30–70%, the annual energy-saving rates are 16–49% and the payback period is 1.7–4.3 years. Therefore, free cooling based on integrated system of mechanical refrigeration and thermosyphon has great application potential for energy-saving of data centers.

In this paper, the possibility on electro-osmosis regeneration of macro-porous silica gel (MSG) desiccant has been investigated by testing the adsorption and electro-osmosis characteristic. The measured saturated moisture content of MSG is 113% in 300 K temperature and 95% relative humidity. Its zeta potential is −10.92 mV, which shows it has both good moisture absorption and electro-osmosis characteristic. The experiment bench is built to test the electro-osmosis regeneration performance on MSG by means of changing initial moisture content (105% and 110%) and applied voltage (40 V, 50 V and 60 V) respectively. The D -value of moisture content between the bottom and upper half with voltage is much higher than that without voltage. For the 110% initial moisture content, there are many visible condensing water droplets on the inside surface of plastic film under the cathode. Based on experimental results, it can find electro-osmosis flow exists when the moisture content is lower than the saturated moisture content. Besides, the electro-osmosis regeneration is one potential method of MSG desiccant when it is applied in dehumidification.

The experimental studies of fin-tube type internally-cooled dehumidifiers are still limited until now. In the present paper, the performance of a cross-flow internally-cooled dehumidifier is studied by both of experiment and simulation. The dehumidifier is made up of fin-tube heat exchangers with high corrosion resistance. Compared with the dehumidifier of the literature, it is found that the dehumidifier of this work performs well in terms of the dehumidification efficiency. Meanwhile, the heat transfer coefficient is correlated on the basis of the experimental data. By applying the correlated coefficient, the theoretical model can predicate the performance of the dehumidifier with an acceptable accuracy. Then the validated model is employed to give suggestions for optimizing the geometry design and operating conditions of the dehumidifier. Through calculation, it is discovered that the best length of the air flow direction for the present dehumidifier is about 0.3 m. In addition, the ratio of solution to air flow rate can be decided by the simulation as well.

A multi-unit heat pump is presented for simultaneous humidity and temperature control to improve the energy efficiency and the thermal comfort. Two parallel connected condensers are employed in the system, locating at the back of the indoor evaporator and the outdoor unit, respectively. The heat pump can operate in four modes, including heating, cooling and dehumidification without and/or with partial or total condensing heat recovery. The experimental investigation shows that the temperature control capacity is from 3.5 kW for cooling to 3.8 kW for heating with the cooling and heating efficiency higher than 3.5 kW kW−1, and the dehumidification rate is about 2.0 kg h−1 with the efficiency about 2.0 kg h−1 kW−1. The supply air temperature and humidity can be simultaneously regulated with high accuracy and high efficiency by adjusting the indoor and/or outdoor air volumes. It provides an integrated and effective solution for simultaneous indoor air temperature and humidity control for all-year-round operation in residential buildings.

Electro-osmotic regeneration for the solid desiccant has been proved to have many merits such as regeneration without the heat source; energy-saving and simple structure. However; the previous work has revealed that its performance is seriously limited by the severe Joule heating effect and electrode corrosion; which demands further improvement to meet the practical requirement. In this paper; four possible improvement methods are investigated experimentally; including changing the material of anode; changing layout of cathode; applying the interrupted power and optimizing the electrical field strength. Through detailed experiments and analysis; we found that applying the platinum-plated titanium mesh as anode could improve the working lifetime from 6 h to over 120 h and effectively reduce Joule heating effect simultaneously; laying a piece of filter cloth under the cathode could enhance the EO regeneration rate up to 0.0021 g s−1; the application of interrupted power could increase the regeneration rate up to 1.5 times; the optimal on–off-time was found at 30 s:1.3 s with 17 V cm−1 electric field strength and 30 s:0.8 s with 11 V cm−1; and the most suitable value of electric field strength was observed as ranging from 8.5 to 13 V cm−1 in our EO regeneration system.

This paper aims to investigate the possibility and performance of a novel electro-osmotic regeneration method for the solid desiccant system, which could adsorb water from the moist air and be regenerated by the electro-osmotic force at the same time, by detailed experimental validation. The zeolite powder with both electro-osmotic and adsorptive characteristics was selected to make the solid desiccant. The quantity of the removed water was measured in the condition with and without an applied electric field to validate the possibility of the electro-osmotic regeneration. The test data show that there was an obvious electro-osmotic regeneration effect in the experiments. The whole electro-osmosis process was divided into three phases because of the Joule heating effect and electrode corrosion, which limited the performance of the experimental system. In particular, a filter cloth under the cathode made a superior electro-osmotic regeneration effect than without the cloth. The experimental results illustrate that the system has the potential of energy-saving and low regeneration temperature. So the electro-osmotic regeneration method is a potential regeneration method for the solid desiccant system.

A steady-state mathematical model of the automotive air conditioning system with a variable-displacement compressor (VDC) is developed to find out the reasons causing evaporator frosting. To validate the system model, a test system is established and the simulated results are compared with experimental data: the predicted results agree well with the experimental data. After analyzing the influence of different factors with the system model, three reasons causing evaporator frosting have been found and corresponding countermeasures have been proposed: (1) the system performance band caused by the frictional forces among the moving components of the VDC can contribute to evaporator frosting, which may be avoided by decreasing the frictional forces between the moving components while designing, manufacturing and operating the VDC; (2) the mismatch between the parameters of the control valve and the resistance pressure of suction pipe or the condenser size can also contribute to evaporator frosting and the control valve with a proper initial compressive force should be selected for a given suction pipe and condenser; and (3) a higher air temperature at the condenser’s inlet may cause evaporator frosting one needs to consider the influence of the air temperature at the condenser inlet while designing the new control valve.