Study on high efficient heat recovery cycle for solid-state cooling

• Proposed the time scale thermal-wave heat recovery concept.
• Conducted theoretical analysis for ideal heat recovery.
• Conducted experiment to validate the proposed thermal-wave heat recovery design.
• Developed a transient model and validated the model by experiment.
• Summarized the limiting factors contributing to the heat recovery efficiency.

Traditional vapor compression cycles (VCCs) use mainly halogenated refrigerants such as hydrochloroflurocarbons and hydrofluorocarbons that are considered as greenhouse gases. Therefore, their regulations are imposed on a global scale. As an alternative cooling technology other than VCCs, solid-state cooling technologies, such as magnetic cooling, thermoelastic cooling and electrocaloric cooling, demonstrate its advantage of not using greenhouse gases as working fluids. However, one of the most challenging issues of these solid-state cooling technologies is the relative high parasitic internal latent heat loss, which could significantly deteriorate the system performance. In order to improve the system performance of solid-state cooling, the authors propose a novel and high-efficient heat recovery (HR) cycle for solid-state materials with high thermal conductivity. The novel heat recovery process was first compared as an analog of spatial scale counter-flow heat transfer process. A simplified ideal model was developed to quantitatively investigate the heat recovery process performance limit and the physics behind the analogy of the spatial scale counter-flow heat transfer process. Experiment was conducted and 60% HR efficiency was achieved. In addition, a detailed dynamic model validated by the experiment results was developed and used to further investigate the limiting factors together with the theoretical analysis.