Experimental Research On Heat Exchange Performance Of In-Tube Spray Evaporative Condenser

Since the 21st century,the pace of China’s modernization has been advancing by leaps and bounds,resulting in a large amount of energy consumption and the problem of energy shortages.This has also promoted the gradual rise of new energy.According to relevant agencies,the proportion of new energy in all energy sources will begin to grow rapidly after 2020.As a kind of clean energy,geothermal energy has great development potential.The geothermal energy in most areas of China is low-medium temperature geothermal energy,power generation through the Organic Rankine Cycle(ORC)is currently the most widely used method of low-medium temperature geothermal energy.Since the power generation efficiency of the Organic Rankine Cycle is lower than that of conventional thermal power generation systems,the condensing system,as an important part of the power generation system,has an important impact on the efficiency of the entire power generation system,so it is necessary to optimize the condensing system.This paper proposes a new type of spray evaporative condenser in tube suitable for ORC power generation system.This paper summarizes the current research progress of evaporative condensers at home and abroad,and conducts a theoretical analysis of the heat and mass transfer mechanism of the proposed new tube spray evaporative condenser,and uses a combination of theory and experiment to conduct research.According to the proposed condenser model,a single-tube experiment platform was built to conduct experiments,and the influence of working fluid temperature,flow,and air volume on the performance of the condenser,the optimal air volume in the tube,and the mass transfer conditions under different working conditions were obtained.In the experiment,the working fluid R245fa and the constant temperature hot water at different temperatures were used to fill the side of the working fluid to conduct heat exchange experiments.The working fluid temperature is 50℃,55℃,60℃,and the heat transfer performance under different air volume and working fluid flow rate is studied.The experimental results show that:within the range of the experimental data,the heat transfer performance is optimal when the air volume is about 6.5m~3/h.At this time,when the working fluid temperature is 60℃,the total heat transfer capacity reaches 270.96W,and the total heat transfer coefficient reaches 279.15W/m~2·K,excessive air volume is not conducive to the evaporation of cooling water in the tube.The heat transfer performance of the working fluid-water heat transfer experiment is better than that of the water-water heat transfer experiment.The maximum consumption of cooling water in the experiment is below 400g/h.The heat transfer performance increases with the increase of the working fluid flow rate,but when the working fluid flow rate reaches a certain value,the heat transfer performance of the experimental system no longer improves significantly.The power consumption and water consumption per unit condensing load of the condenser proposed in this paper are calculated,and compared with the air-cooled,water-cooled and traditional evaporative condensers,the power consumption of the experimental system is obtained as 2.21W/k W,of which the fan power consumption is2.2 W/k W and the water pump power consumption is 0.04 W/k W.Compared with air-cooled,water-cooled and traditional evaporative condensers,the condenser saves 30.45W/k W,22.37 W/k W,and 8.88 W/k W.The average water consumption of the experimental system is about 0.41g/s,which is 0.578g/s lower than that of the water-cooled condenser.In addition,the daily operating costs of the experimental system and the traditional condensers of various forms are calculated and economically compared according to the energy price:the unit condensing load can save 0.7973 yuan per day compared with the water-cooled type,0.2737 yuan compared with the air-cooled type,and 0.1744 yuan less than the traditional evaporative condenser.The new tube spray evaporative condenser proposed in this paper has great economic benefits,and it also provides a reference for future large-scale research and production.