Research On Heating Performance Of Gas-supplement Lithium Bromide Absorption Heat Exchanger

The application of absorption heat-exchange technology in the district heating network can significantly reduce the temperature of return water in the primary network and improve the heating capacity of the heating network.However,with the increasing demand for heat supply,conventional single-segment absorption heat exchanger units will not be able to meet the user-side demand for heat due to limitations in the solution's own temperature,concentration,and bleed air range.In order to solve the problem of insufficient heating capacity of the heating network,a series-combustion-type waterlithium bromide absorption heat exchanger is proposed in this paper.Based on a conventional single-segment absorption heat exchanger,a direct-fired absorption type is added to this unit.The heat pump achieves a lower net return water temperature,which further increases the heating capacity of the heating network.Based on the analysis of the system structure of the gas-supplement absorption heat exchanger,eight types of unit form are constructed according to the different configurations of the unit's secondary water circulation.Through analysis of feasibility and rationality,the connection of the absorber A₁-the absorber A₂-the condenser C₁-the condenser C₂ in series is selected to be the object of study of this subject.The mathematical model of the unit is established by analyzing the thermodynamic cycle and heat transfer process of the gas-supplement absorption heat exchanger.Based on the technically feasible minimum heat-transfer terminal difference,a method for solving the maximum heating capacity of the gas-supplement absorption heat exchanger is proposed,and the distribution law of the heat exchange amount in the unit is quantitatively analyzed.The maximum heating capacity of the single-segment absorption heat exchanger and the the gas-supplement absorption heat exchanger is compared with the expansion factor of the heat supply of the traditional plate heat exchanger.The expansion factor of the former is basically maintained at 1.5.The latter's expansion factor is approximately 3.3.An optimization design method and procedure for the gas-supplement absorption heat exchanger is proposed.The total cost of the unit is taken as the objective function,and the optimized constraints were determined according to the technical conditions and economic conditions of the unit.The algorithm acts as an optimization algorithm.The above optimization design method is applied to the actual project,and it is concluded that the optimal unit heat exchange cost of the unit is 45.295 yuan /kW.A study on the operation simulation of the gas-supplement absorption heat exchanger,and quantitatively analyzed the operating characteristics of the unit under different load conditions under the premise of meeting the heating demand.Impact,the results show that under all load conditions,a single water inlet temperature has a more significant effect on the primary outlet temperature,while the primary water flow has a more significant effect on the unit gas consumption.The research results of this topic can provide the theoretical basis for the optimal design of the gas-supplement absorption heat exchanger,and through the analysis of the operating characteristics of the variable working condition,it can provide reference for the operation and debugging of the unit in actual operation.