Effects of Temperature Differences in Optimization of Spiral Plate Heat Exchangers

In this research, three aspects of modeling, analyzing, and optimizing spiral plate heat exchangers (SPHEs) are studied. The main objective of this work is to pave the way for comparing manufacturers' designed SPHEs with theoretical designed SPHEs without involving designers in using computational methods. To begin, with assumption of constant overall heat transfer coefficient and specific heat capacities, a mathematical modeling of SPHE based on energy balance equations is developed to model the SPHE as a network of series-connected equivalent internal heat exchangers to determine the temperature distribution in spiral turns. This modeling can facilitate the usage of temperature-enthalpy diagram in SPHEs' analysis and design. Furthermore, a new algorithm for thermal design optimization of SPHEs has been proposed. The proposed algorithm is based on maximizing pressure drops at channels, considering geometric proportion of SPHE and minimizing the total cost simultaneously. To show the proposed method applicability in analyzing thermal and hydraulic design parameters, a single-phase counter-current SPHE is assessed and optimized for different design cases with temperature approach variations. Results of comparing manufacturers'/standard designed SPHEs and research/theoretical designed SPHEs by defining appropriate geometric proportion ranges confirmed that temperature approach variations can improve SPHE performance to a higher extent, such as finding temperature approach ranges for optimized SPHEs with higher compactness to reduce the manufacturing cost. This fact is revealed by introducing compactness-temperature approach diagram which depicts the geometric optimization of SPHEs and the effects of temperature differences in SPHE's optimization.