The Flow And Heat Exchange Characteristics Of Printed Circuit Board Heat Exchangers Are Studied

As the basic equipment of energy transfer,heat exchanger plays an important role in production.The printed circuit heat exchanger（PCHE）is a new type of high-efficiency microchannel heat exchanger,which is suitable for high temperature and pressure working environment and can reduce the footprint and save the overall layout space.In this paper,supercritical carbon dioxide（CO₂）was used as the working medium,and based on the REPFROP database,the thermal properties of supercritical CO₂ under constant pressure（13.6MPa）were fitted into a piecewise function about temperature,and the physical properties of supercritical CO₂ were customized.The main work of this paper is as follows:（1）In this paper,the flow and heat transfer characteristics of supercritical CO₂ in the PCHE direct current channel were numerically studied,and the effects of different flow channel depth,cross-section shape,inlet temperature,and heat flux on heat transfer performance were studied.The comprehensive heat transfer performance of the runner was compared by comprehensive evaluation index（PEC）.The numerical calculation results show that under the same flow condition when the runner depth increases from 0.55mm to 0.95mm,the PEC value decreases by 37%.The influence of the change of flow passage cross-section shape on PEC is 6%.PEC decreases with the increase of heat flux.（2）The flow and heat transfer characteristics of supercritical CO₂ in a PCHE sinusoidal channel were numerically studied,and we studied the effects of different angular frequencies,amplitudes,and different flow channel combinations on heat transfer performance.Under the same pressure drop condition,the comprehensive heat transfer effect of a sinusoidal channel with an angular frequency of 1/2 is 7.7%higher than that of a sinusoidal channel with an angular frequency of 1.The comprehensive heat transfer effect of a sinusoidal channel with an amplitude of 1.5 is 5.2%higher than that of a sinusoidal channel with amplitude of 1.The comprehensive heat transfer effect of Model B is 24.8%higher than that of Model D.（3）The flow and heat transfer characteristics of supercritical CO₂ in the PCHE discontinuous channel were numerically studied,and the influence of different fin height,fin shape,and fin arrangement on heat transfer performance was studied.The finned height of 0.2mm PEC is 10%higher than that of smooth pipe.When the height of the fin is greater than 0.2mm,the PEC decreases instead.The PEC of the improved rhombus fin model is 22.3%higher than that of the drop fin model.The comprehensive heat transfer effect of the staggered arrangement is better than that of parallel arrangement.