| Summary: | The printed circuit heat exchanger (PCHE) has been used in many important engineering applications because of its advantages, including its small size and high efficiency. This study aims to enhance the thermohydraulic characteristics of the PCHE by using new channels characterised by a three-dimensional flow path. These proposed backward/forward-facing wavy channels (BFFWCs) are a combination of a wave path in the horizontal plane and a U-shape path in the vertical plane. Under laminar water flow on both sides of the PCHE, a numerical study was conducted to assess the thermohydraulic characteristics of the proposed PCHEs with various wave amplitudes for channels and angles of attack for six models of BFFWCs on the basis of the conventional PCHE. The evaluation parameters that were adopted are the Nusselt number, friction factor, thermohydraulic performance criterion, and PCHE's effectiveness. Two models of the PCHE were manufactured and tested—one for the straight channels and the other for the proposed channels—to verify the accuracy of the numerical simulation results by comparing them with the experimental outcomes. Results indicated that the three-dimensional flow path has a positive influence on enhancing the heat transfer rate of the exchanger, with a slight increase in the pressure loss. The Nusselt number and friction factor increase with increasing wave amplitude and angle of attack. Compared with conventional PCHE, the maximum improvement in the Nusselt number is as much as 71 % and 78 % for model 3 (amplitude = 0.8 and angle of attack = 30°) and model 6 (amplitude = 0.8 and angle of attack = 60°). The thermohydraulic performance of model 3 was better than that of model 6. The maximum obtained thermohydraulic performance criterion reaches about 1.43 and 1.40 for models 3 and 6, respectively.
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