Simulation study of solid-liquid phase change in regenerative heat exchanger with finned tubes
Existing waste heat recovery technology is relatively backward in low-temperature waste heat recovery,so a low-temperature heat-storage heat exchanger was designed with the input heat fluid of 90℃water and phase change material of 60#paraffin wax.Fluent was used to simulate the heat storage and release with different sizes and numbers.The results showed that after 500 s of heat storage,average liquid fraction of integrate finned heat exchanger was 45.5%and 81.3%more than small finned heat exchanger and no finned heat exchanger;after 500 s of heat release,outlet water temperature of integrate finned,small finned and no finned heat exchanger were 0.5℃,0.4℃,0.2℃higher than initial value,respectively.Integrate fins showed the most stable and best heat exchange ability,based on which a study on the number of tubes carried out.It was found that with 1,2,3 fin layers,after 1 000 s of heat storage,average liquid fraction were 0.36,0.47,0.58;after 500 s of heat release,outlet water temperature were 0.21℃,0.26℃,0.36℃higher than initial value.Obviously,heat exchange efficiency,average melting and condensation rate of phase change material and stability were enhanced as number fin size and layer increased,can provide technical guidance for waste heat recovery in the low-temperature waste heat recovery.
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