Heat Exchanger’s Selection And Technology Research Apply To Oil Screw Air Compressor Heat Recovery

Abstract:When air compressor produced compressed air,about 15% of electricity had been used for compressing air.however, the rest part of electricity (nearly 85%) was lost in the air through the forms of radiation,convection,heat conduction.Finally, it caused a great waste of energy. The technology of air compressor’s waste heat recovery was using plate heat exchanger as heat exchange equipment to recycle the wasted heat. On the basis of the predecessors’research, ε-NTU method was proposed for the selection on plate heat exchanger to recycle waste heat that in shanxi textile mill,and then reformed the air compressor system. After the waste heat recovery system had been finished and the principles on plate heat exchanger’type selection formula were studyed, we can get this conclusion:while Reynolds number is fixed, there was a linear relationship between parameter C and m in heat exchanger’s criterion equation.So, in this circumstance, we could determine the accurate criterion equation of a specific heat exchanger on experiment testing.With test data for quadratic fitting, we obtained accurate ratio to specific heat exchanger heat transfer principles. Above the criteria ratio, the oil screw air compressor recovery of waste heat selection formula was settled. Comparing the actual heat transfer coefficient, as well as the selection of the relationship between the calculation of the heat transfer coefficient, confirmed the valid rule of this type plate exchanger. Finally completed he whole system, when the system run a year later,we found that a lot of hot water wasted in the summer.In order to collect those heat,a LiBr absorption chiller was add to refrigerate. Useing May to August temperature as a reference,then,carried on a series of theoretical calculation, concluded the daily refrigerating capacity per month. And chose the biggest refrigerating capacity to calculate economic analysis. Concrete results are as follows:(1) According to air compressor model LS-25S-350H,carried on heat plate heat exchanger type selection,select xi’an company’s heat exchanger of BR01-1.0-4(2)when Reynolds number was fixed, adopt method of plate heat exchanger BR01-1.0-4 experimental tests, after the data processing method of least square fitting criterion equation for the heat exchanger heat transfer, Nu=0.01767Re0.887 Pr0.4(加热流体)Nu=0.01767Re0.887 Pr0.3(冷却流体)(3) Based on the experiment of the criterion equation of heat transfer, a sullair LS-25S-350H heat recovery system show that the calculated of plate heat exchanger heat transfer coefficient is 181.33, compared with design of the heat transfer coefficient 133.33,we can consider the temperature error between imports and exports is in accept range. Coefficient of heat transfer calculation under this heat transfer plate number for 60 pieces, similar to the selection. Therefore, prove the correctness of the rule of the number, the specific plate heat exchanger BR01-1.0-4 selection of the universal formula.(4)When using waste heat as driven heat source,the LiBr absorption chiller refrigerating capacity is 84.21 kW, which was equivalent of 1.5P air conditioning refrigerating 24 capacity.So, electricity consumption can be accumulated for ten (11.27-12.68)thousand yuan, LiBr is only 2.876 million yuan, greatly save the energy.