In the vapor compression heat pump system, the power consumption of the compressor determines the overall power consumption. If a good compressor control technology can be developed, huge energy costs can be saved. This paper is based on the experimental method research, and develops a heat pump system of variable screw compressor Vi, which uses the modulation Vi to control the compression ratio of the matching system operating conditions, the compressor variable frequency control and the expansion valve opening degree control to optimize the system operation. , the experimental benchmark conditions are established by using the field design maximum hot water outlet temperature of 55 ℃, the properties of R134a refrigerant, and the different compression ratios of each working condition with the compressor modulation Vi and other conditions.
The linear trend results of the experimental study show that when the system compression ratio is less than 3.5, the average adiabatic compression efficiency of Vi2.4 is better than Vi3.0 by about 5.08% and Vi3.5 by about 10.56%; it is better than Vi3.0 by about 2.98% And Vi3.5 about 10.77%; and when the system compression ratio is 4.5, the adiabatic compression efficiency of Vi3.5 is better than Vi2.4 about 7.09% and Vi3.0 about 0.10%, better than Vi2.4 about 11.38% and Vi3.0 is about 9.40%. At 55°C hot water outlet temperature, the power consumption of Vi3.5 compressor is about 2.76% less than that of Vi3.0, and about 7.57% less than that of Vi2.4.
In recent years, with the vigorous development of science and technology, people gradually began to rely on computers and various electronic devices to process a large amount of information, and data centers process a large amount of data behind this information every day, accompanied by a large amount of power consumption and environmental impact. of destruction. In order to explore the energy-saving plan of the data center, this study uses the computational fluid dynamics software ANSYS Fluent to simulate the flow field in the data center, and uses the Taguchi method for analysis. Each factor has three levels of change, so an orthogonal table is selected, and nine groups of cases are simulated according to the orthogonal table.
In order to increase the return water temperature of the cooling system, three quality characteristics, the average temperature of the hot air duct, the temperature difference between the highest and the lowest temperature in the hot air duct, and the average temperature difference between the hot and cold air ducts, are selected as the optimization targets, and the grey relational theory is used to find out the quality characteristics under various quality characteristics. , and finally simulate and verify the optimization results. The results show that the factor levels of the optimized case are that the server position is concentrated at the bottom, the air is supplied from the bottom, the air supply flow rate is 800CMH, and the air supply temperature is 288.15K. The temperature difference between the highest and lowest temperature = 2.52K and the average temperature difference between the hot and cold air ducts = 11.06K.
Keywords: data center, computational fluid dynamics, Taguchi method, grey relational analysis
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The team built a small heated suction dryer to test the state of the air flow in and out of the system when compressed air is dehumidified with any adsorption desiccant, and developed an algorithm to calculate the same desiccant used in suction dryers of any capacity. The energy consumption value of the system. In this paper, the energy consumption value of two desiccants is evaluated by this method: activated alumina and a metal organic framework (MOF) material developed by our team. According to the analysis results, 7 kg/cm2. The energy consumption of using the metal-organic framework of our team is about 92% of the alumina used when the compressed air is dried to the pressure dew point ≦ -20°C after preliminary dehumidification by the cold dryer. The reason for this should be that the regeneration temperature required for the metal organic framework is lower than that of alumina.
Keywords: suction dryer, metal organic framework, activated alumina, energy saving
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In this study, the non-conductive fluids FC-72 and HFE-7100 were used to investigate the condensation heat transfer performance outside the tubes, and to simulate the condensation conditions of the immersion computer cooling system. There are four types of tubes: round tube, smooth elliptical tube, reinforced round tube and reinforced elliptical tube, and the condensation phenomenon is observed by visual cavity. The cooling water flow in the tube is 1.5 and 2LPM. The experimental results show that FC-72 and HFE-7100 have the highest condensation heat transfer coefficient in the elliptical reinforced tube. Overall, the condensation heat transfer of FC-72 is better than that of HFE-7100, and the highest condensation heat of FC-72 and HFE-7100. The transmission coefficient can reach 3400 and 2491W/m respectively2K. Compared with the surface type, the condensation heat transfer coefficient of the reinforced tube is higher than that of the smooth tube; compared with the cross-sectional shape of the tube, the condensation heat transfer coefficient of the elliptical tube is higher than that of the circular tube; because of the large curvature of the wall surface, the condensation film on the tube wall Affected by gravity, it is easier to detach from the surface of the condensing pipe, so that the condensing pipe is not easy to thicken due to the increase of condensation amount, and can maintain better heat transfer performance.