IV INTERNATIONAL CONFERENCE ON ENGINEERING AND NATURAL SCIENCES (ICENS), Kiev, Ukraine, 2 - 06 May 2018, pp.397
In order to increase the energy efficiency in ship operations, the waste heat recovery systems (WHRS) that recover heat from ship’s main engine exhaust gases are commonly used. Because conventional shell and tube heat exchangers are heavier and take up larger space, the usage of micro-channel heat exchangers, namely diffusion-bonded printed circuit heat exchangers (PCHE) has gained much attention recently in the maritime industry. They are also popularly used in nuclear power plants because of their advantages of having higher surface-area-to-volume ratio, higher pressure/temperature resistance and higher heat transfer efficiency. Predicting the heat transfer coefficient and the pressure drop in micro-channels is of a great importance in designing PCHEs and optimizing the power cycles. Modification of the geometrical characteristics of the heat exchangers and the variation of the thermal properties of the running fluid with high temperature are crucial factors in thermo-hydraulic design of PCHEs. In this study, the thermal and hydraulic performances of PCHE with different micro channel characteristics were investigated at different Reynolds number. Numerical analysis were conducted with k – ω turbulent model using a commercial CFD code, ANSYS CFX. Finally, a comparison with mathematical model is made. NTU-effectiveness method is used in designing and conducting the thermal-hydraulic performance analyses of the heat exchangers. The comparison is made for specified initial pressure and temperature conditions. Using compact PCHEs in ships has been found to be advantageous in terms of weight, system layout, maintenance & operation, cost and thermal-hydraulic performance.
Keywords: Compact heat exchangers, Printed circuit heat exchanger, Waste heat recovery system