最新刊期
卷 33 ， 期 3 ， 2012
- 摘要：As a new type of two phase secondary refrigerant, CO2 hydrate slurry has a good application prospect in air conditioning system with cool storage for its efficient and reasonable shift of power peak. Usually it is produced by pressurization and bubbling gas in a vessel which is simple and energy conservation. In addition, CO2 hydrate slurry has a good performance in cool storage and phase change temperature. According to performance of non-Newtonian fluids, this work summarizes the rheology equation of CO2 hydrate slurry, lists the calculation method of apparent viscosity and rheological index and points out the excellent flow characteristic of CO2 hydrate slurry.关键词：pyrology;cools torage;two phase secondary refrigerant;hydrate slurry;apparent viscosity1678|2240|0发布时间：2024-07-18
- 摘要：Air flow noise is an important parameter influencing the amenity of indoor environment, which is mainly caused by the cross flow fan in the indoor unit of air conditioners. The noise prediction method is presented by integrating the unsteady flow field simulation and aerodynamic noise model. The unsteady incompressible Navier-Stokes equation is solved with RNG k-ε turbulence model with a sliding mesh technique. The aeroacoustic pressure is calculated by Ffowcs-Williams and Hawkings equation. The unsteady pressure data, which is calculated from the unsteady flow field, is used as input data for the FWH equation. This method is applied to analyze the unsteady flow field and flow noise of the cross flow fan in the indoor unit, and the predicted sound pressure level and acoustic spectrum agree well with the measured data not only total noise but also broadband noise. These results show that this numerical method can be used as an effective tool for optimization of axial fans for compact design, large air volume and low noise.关键词：Power machinery and engineering;Air-conditioner;Noise;Fan;simulation;CFD1810|2143|0发布时间：2024-07-18
- 摘要：In order to reduce energy consumption of air-conditioner during night, one zoning air-conditioner fixed on the bed, namely bed AC, is developed based on peltier effect. The bed AC is equipped with a heating unit on the foot part and a cooling unit on the head part. It not only meets the thermal comfort of a bed, but also can create a comfortable environment about “warm foot and cool head”. In winter, bed AC can maintain bed air temperature at 22℃, and its power is about 0.1kW~0.2kW, and foot air temperature is approximately 6℃ higher than that of head. In summer, if room temperature is lower than 30℃, bed AC can keep bed air temperature at 28℃, and its power varies from 0.06kW to 0.12kW, and head air temperature is nearly 1.5℃ lower than that of foot. By system simulation, the energy-saving performance is also studied. It can be found that energy saving rate of bed AC in winter and summer sleeping time is 52% and 42% respectively, compared with traditional split air-conditioner.关键词：pyrology;Peltier effect;bed air-conditioner;cool head and warm feet1801|2028|0发布时间：2024-07-18
- 摘要：The design process of the air cooler used in refrigerated warehouse is introduced in detail and optimization algorithms are used to optimize the structure of the air cooler of CO2. Volume and the heat transfer coefficient of the heat exchanger are taken as an object function respectively, and fin-pitch, tube distance, tube rows, row numbers, diameter of heat pipe and the lengths of single pipe are selected as decision variables. However, according to the results of optimization, both the two algorithms are defect and insufficient, so the structure of the CO2 air cooler is optimized by the multi-objective optimization with the heat transfer coefficient, volume, air-side pressure drop. It shows that the multi-objective optimization is effective with the weight coefficients. The optimization results are verified by the experiments. Finally, the sensitive analysis of the structure is given based on the optimal result above.关键词：pyrology;optimization;air cooler;structural parameter2096|2056|0发布时间：2024-07-18
- 摘要：HFE143m is a novel environment friendly refrigerant, but domestic research on it is very limited. Thermophysical properties correlations of HFE143m and comparison of cycle performance between HFC134a and HFE143m are given in this paper. The results show that the operating pressure of HFE143m is lower than that of HFC134a. The per unit mass cooling capacity and the coefficient of performance (COP) are improved 2.9% and 3.6%, respectively, under the isentropic compression condition. The per unit mass cooling capacity and the COP are improved 2.9% and 16.6%, respectively, when the compressor outlet superheat is 25℃. This novel refrigerant has the potential to replace HFC134a.关键词：engineering thermophyics;new refrigerant;HFE143m;thermophysical properties;cycle performance1971|2237|0发布时间：2024-07-18
- 摘要：The composite absorbent is mainly consisted of attapulgite and CaCl2 as the resources, which were prepared by the dissolution-mixed method, and the content of attapulgite in composite absorbent is 10%. Adsorption isotherms of ammonia on absorbents were determined by positive gravimetric method. Adsorption-desorption cycle performance and cooling characteristics of composite absorbent -ammonia working pairs was evaluated by self-made adsorption-desorption measuring device. Experimental results show that the equilibrium capacity of ammonia on the composite absorbent is up to 1.1kg/kg at 30℃, which is equal to that of CaCl2. The conditions of loading density 600kg/m3, adsorption temperature 30℃, ammonia evaporation pressure 0.25 MPa, desorption temperature 300℃, adsorption capacity of ammonia in the composite absorbent and its cyclic adsorption capacity is 0.89~0.92 kg/kg and 0.55~0.58 kg/kg, respectively, which is 1.7 times than that of CaCl2-ammonia working pairs. The cooling capacity is up to 761.84kJ/kg, which is increased by 70% compared to CaCl2/ ammonia. What’s more, composite absorbent has excellent adsorption and desorption stability.关键词：engineering thermophyics;composite adsorbent;adsorption capacity;cooling capacity;attapulgite1779|1941|0发布时间：2024-07-18
- 摘要：The growth process of tetra-n-butyl ammonium bromide solution on copper surface has been investigated. The temperature curves of water and tetra-n-butyl ammonium bromide hydrate in different concentration were obtained. The growth process was monitored by microscopic and the digital photos were caught by CCD camera. Combined with the temperature curves,these photos were compared and explained.The results revealed that the position of crystallization on the copper surface is stochastic. It was found that Type A crystals formed easier than Type B crystals in 10% TBAB solutions. While in 20% and 30% solutions, Type A crystals and Type B crystals formed simultaneously. The growth velocity of the crystals is related to the texture of the copper surface.关键词：engineering thermophysics;growth process;visualization;water;hydrate2040|2338|0发布时间：2024-07-18
- 摘要：More and more attentions are being paid on ATRCT (Aluminum Tube Replacing Copper Tube) in the air conditioning field currently, which is necessary to be carried out because condenser is the device using a lot of copper materials in the air conditioning. Correctness of heat-transfer theory calculation model was verified through the theoretical calculation and the experimental analysis of sheet condenser with ATRCT, and heat-transfer characteristics were studied. The results show that thermal contact resistance between aluminum tube wall and fins has little influence on heat exchange in the study, however, the internal coefficient of condensation in refrigerant tube has a great impact on that, which is also validated by the surface temperature experiments. The ideal coefficient in the internal condensation equation of aluminum tube condenser was obtained according to the experimental data fitting.关键词：engineering thermophysics;aluminum replacing copper;heat-transfer characteristics;condenser;refrigeration system1813|3033|0发布时间：2024-07-18
- 摘要：Heat transfer enhancement from a horizontal rectangular fin embedded with circular perforations under natural convection is studied. Through the experiment and simulation, the heat dissipation power of different perforated numbers was compared to the equivalent solid one. Despite the perforated number, the perforated location, size and shape were also considered in heat transfer enhancement. It is shown that the perforated fin is superior to the solid. And with the increase in the number of perforation, the heat dissipation power increases first and then decreases. There is an optimal perforated number 7. Its heat dissipation power increases by 13.25% comparing with the corresponding solid fin. When the perforated location is at the bottom, the heat dissipation power is the best. Then the middle is the second and the top is the worst. Within the scope of the study, with the increase of perforated radius, the heat dissipation power increases first and then decreases. When the perforated radius is 7mm, the heat dissipation is the biggest. Its heat dissipation power increases by 13.25% comparing with the corresponding solid fin. And comparison of the triangular, square and circular perforations with the same areas, the heat dissipation of the circular perforations is the best.关键词：engineering thermophysics;natural convection;rectangular fin;perforation;heat transfer enhancement;radiation2173|2174|0发布时间：2024-07-18
- 摘要：In order to reduce the performance degradation caused by the heat loss of reversing valve in heat pump air conditioning system, a method of substituting lower thermal conductivity valve seat for present commonly used ones was proposed. The energy saving effect of lower thermal conductivity valve seat was analyzed through experiments and simulations. Research results show that, the heat loss of the present commonly used reversing valve can not be ignored; considering the effect factors of structure design and processing technology, it is a feasible method to reduce heat loss by using reversing valve seat with lower thermal conductivity; when thermal conductivity of reversing valve seat decreases from 110 W/(m.K) to 60 W/(m.K), the heat loss of reversing valve decreases by 21%, and the COP of heat pump system increases by 0.4%.关键词：pyrology;heat pump air conditioning system;reversing valve;valve seat;energy saving1695|2041|0发布时间：2024-07-18
- 摘要：In recent years, some papers have studied the vacuum cooling of food using small experimental devices. However there are some inappropriate measures in these experiments, such as improper food applications, unsuitable sample number of food, inadequate vacuum degree and too much water loss. Therefore, whether the obtained data and conclusions can be applied to actual production still need further consideration. Based on the thermodynamic analyses of vacuum cooling, this paper introduces its main applications, and analyses the vacuum pressure, cooling rate and water loss of foods.关键词：Food package and preservation;vacuum cooling;pre-cooling;thermo dynamical analysis;water loss rate1706|1960|0发布时间：2024-07-18
- 摘要：Numerical study of three-dimensional flow field was carried out for the duct system of the floor standing air-conditioner. Comparative study on three types of structure of bell mouth used in the multi-blade centrifugal fan was implemented. Calculation results show that, both the first type of bell mouths with the inward inlet whose axial height is larger than the existing type and the second type of bell mouth with new mold line inward inlet and smaller slope angle than the existing type can improve airflow utilization ratio and reduce the vortex in the back of volute exit compared to the existing type, and the air volume is increased by 6.8% and 4.2% respectively. The experiment was carried out to validate the result of simulation and the experimental results show that the air volume can increase by 4.7% and 3% respectively while the level of noise is invariant.关键词：pyrology;numerical simulation;Air-conditioner;bell mouth;multi- multi-blade centrifugal1700|1986|0发布时间：2024-07-18
- 摘要：Different types of sugar alcohol is usually used as cryoprotective agents (CPAs) to preserve human hepatocytes. In this study, a new types of sugar alcohol based CPAs with low toxicity was explored by replacing Me2SO with D-sorbic alcohol, xylosic alcohol and maltol. The Me2SO concentration in CPAs was reduced to 5%. Human hepatocytes attached to plastic cover slips were treated with the above CPAs and then placed in the fridge at -80℃ for two weeks. The survival rate, 24h cell detachment and cell morphology were tested and compared with the results using 10% Me2SO as CPAs. The results show that 5% Me2SO with D-sorbic alcohol gives the best results. It is concluded that the new CPAs are effective to human hepatocytes cryopreservation.关键词：medical cellular biology;cryopreservation;hepatocyte;sugar-alcohol;dimethyl-sulfoxide(Me2SO)1835|1916|0发布时间：2024-07-18
- 摘要：To further understand the energy quality utilization of air conditioning and heating system, the exergy analysis based on specific consumption analysis was studied. The exergy coefficient computational methods of some typical air conditioning and heating systems (boiling heating, electric heating, heat hump, absorption unit) were studied, and the general formula of exergy coefficient was summarized. To express mean exergy coefficient of the whole season, two mean exergy coefficient computational methods for air conditioning and heating system were proposed: heat weighted temperature method and fuel weighted method, and so the exergy analysis for air conditioning and heating system was improved. By taking the heating in Beijing as an example, the First & Second Law of Thermodynamics based coefficients of typical air conditioning and heating systems were developed, and from these numerical values, the energy (quality) utilization of air conditioning and heating systems in different loads was fully obtained.关键词：engineering thermophysics;mean exergy coefficient;specific consumption;air conditioning & heating system1745|2198|0发布时间：2024-07-18
- 摘要：Using the tenderloin of pork as the raw materials, the aerobic bacterial count, physicochemical parameters such as total volatile base nitrogen, drip loss, water retention rate, pH and sensory evaluation, the fresh-keeping quality of pork were compared under steady -2℃(partial frozen), 4℃(cold storage) and -18℃(frozen storage). The results show that partial frozen pork could keep the first grade of freshness for 15d and the second grade of freshness for 27d, while 4℃ was only 6d. -2℃ (partial frozen) pork had less drip loss, higher water retention rate and more acceptable sensory compared with that frozen stored at -18℃. So partial frozen can be an effective method for keeping freshness of pork.关键词：food processing technology;partial frozen;cold storage;frozen storage;pork1780|2187|0发布时间：2024-07-18
- Address：10/F, Yindu Mansion, 67 Fucheng Road, Haidian Dist, Beijing, China Postal code：100142
- Tel：010-68711412 Email：editor@car.org.cn
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备09064830号-19
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0