Energy flow-based method for analysis and optimization of evaporative cooling and ventilation systems

摘要

Physical and mathematical models significantly affect the ease of system analyses and optimization. This contribution presents a modified thermal resistance model for an evaporative cooling process and establishes an energy flow model analogous to an electrical circuit for an indirect evaporative cooling and ventilation (IECV) system based on the overall energy transport. The system modeling equations based on Kirchhoff's laws are a set of linear algebraic equations that characterize the relationships between each component in the system. They are applied as system constraints in the Lagrange multipliers method to optimize the design. The optimization minimizes the total thermal conductance for a fixed cooling capacity and total circulating water mass flow rate. The solutions of the optimization equations for a typical IECV system give a set of Pareto frontiers that reflect the trade-off between the thermal conductance and the mass flow rate, which represent the investment cost and the operating cost. Optimizations with various cooling capacities, indoor temperatures and ambient air conditions reveal their impacts on the optimal parameter allocations. Therefore, this application of the energy flow model shows its advantages for both performance analyses and system optimization. (C) 2019 Elsevier Ltd. All rights reserved.