Comparison of shell-and-tube with plate heat exchangers for the use in low-temperature organic Rankine cycles

• Published in: Energy conversion and management Vol. 87; pp. 227 - 237
• Main Authors: Walraven, Daniël, Laenen, Ben, D’haeseleer, William
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.11.2014; Elsevier
• Subjects: Allocations; Applied sciences; Devices using thermal energy; Electric power generation; Electric power plants; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Heat exchangers; Heat exchangers (included heat transformers, condensers, cooling towers); Inlet temperature; Optimization; ORC; Plate heat exchanger; Plate heat exchangers; Pressure drop; Shell-and-tube heat exchanger; System optimization; ORC; Shell-and-tube heat exchanger; Plate heat exchanger; System optimization; Tube; Heat exchanger; Rankine cycle; Tube plate; Optimization; Low temperature
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2014.07.019

•Binary cycles for low-temperature heat sources are investigated.•Shell-and-tube and plate heat exchangers are modeled.•System optimization of the cycle variables and heat exchanger geometry.•ORCs with plate heat exchangers obtain in most cases higher efficiencies. Organic Rankine cycles (ORCs) can be used for electricity production from low-temperature heat sources. These ORCs are often designed based on experience, but this experience will not always lead to the most optimal configuration. The ultimate goal is to design ORCs by performing a system optimization. In such an optimization, the configuration of the components and the cycle parameters (temperatures, pressures, mass flow rate) are optimized together to obtain the optimal configuration of power plant and components. In this paper, the configuration of plate heat exchangers or shell-and-tube heat exchangers is optimized together with the cycle configuration. In this way every heat exchanger has the optimum allocation of heat exchanger surface, pressure drop and pinch-point-temperature difference for the given boundary conditions. ORCs with plate heat exchangers perform mostly better than ORCs with shell-and-tube heat exchangers, but one disadvantage of plate heat exchangers is that the geometry of both sides is the same, which can result in an inefficient heat exchanger. It is also shown that especially the cooling-fluid inlet temperature and mass flow have a strong influence on the performance of the power plant.