Heat transfer and flow resistance analysis of a novel freeze-cast regenerator

Liang, Jierong; Christiansen, Cathrine Deichmann; Engelbrecht, Kurt; Nielsen, Kaspar Kirstein; Bjørk, Rasmus

doi:10.1016/j.ijheatmasstransfer.2020.119772

Cited by 19 publications

(15 citation statements)

References 69 publications

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“…Freeze-cast regenerators #1, #2 and #3 are compared experimentally in order to investigate the flow resistance, heat transfer performance, cooling capacity, regenerative temperature lift and mechanical stability. Relevant data regarding regenerator #4 may be found in our previous study (Liang et al, 2020).…”

Section: Resultsmentioning

confidence: 75%

“…The parameter f osc is the oscillatory friction factor based on the maximum pressure drop consistent with the correlations. Through the passive experiments, Nu and f osc have been correlated through model fitting based on a single regenerator previously reported (Liang et al, 2020). The parameters in the correlations are further validated by variable geometrical parameters, such as the pore size.…”

Section: Passive Characterizationmentioning

confidence: 90%

“…Three regenerators (#1, #2 and #3, Figure 1) were fabricated by freeze-casting under similar conditions to our previous study on freeze-cast regenerators (regenerator #4) (Liang et al, 2020). A ceramic suspension for freeze-casting was prepared from 30 vol% of LCSM06 (CerPoTech, Norway) in MiliQ water with 2.5 wt%, solid to ceramic ratio, of dispersant (DURAMAX TM D-3005, Rohm and Haas, Dow Chemical, USA).…”

Section: Regenerator Preparation and Geometric Characterizationmentioning

confidence: 99%

“…The three new regenerators are compared with our previously published regenerator (#4), and all the geometrical parameters are summarized in Table 1. The structural features of the freeze-cast regenerators were characterized by image analysis of micrographs, as described in detail in previous studies (Liang et al, 2020). Micrographs were obtained using a scanning electron microscope (TM3000, Hitachi High-Technologies).…”

Section: Regenerator Preparation and Geometric Characterizationmentioning

confidence: 99%

“…To achieve a more in-depth investigation of freeze-cast regenerators, this study focuses on identifying the proper pore size and the corresponding operating conditions. A freeze-cast regenerator identified as having small hydraulic diameter and which may be manufactured with thin walls, was preliminarily studied previously (Liang et al, 2020), with focus on the heat transfer potential of freeze-casting ceramics applied in a passive regenerator. From zero applied field test of a single sample, the main advantage of the freeze-cast regenerator is the excellent heat transfer performance due to the small hydraulic diameter and large specific surface area.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Freeze-Cast Micro-Channel Monoliths as Active and Passive Regenerators

et al. 2020

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The efficiency of the magnetic refrigeration process strongly depends on the heat transfer performance of the regenerator. As a potential way to improve the heat transfer performance of a regenerator, the design of sub-millimeter hydraulic diameter porous structures is realized by freeze-cast structures. Four freeze-cast regenerators with different pore widths are characterized experimentally and numerically. Empirical parameters are determined for the correlations of heat transfer and flow resistance via a 1D model. Thermal effectiveness and pressure drop are measured for thermal-hydraulic evaluations. Temperature span and specific cooling capacity are obtained to compare the magnetocaloric potential based on the material La0.66Ca0.27Sr0.06Mn1.05O3. The stability of freeze-cast regenerators is validated by comparing the performance during, before and after oscillatory flow and periodic magnetic field tests. Smaller pore design obtain the better heat transfer performance and required mechanical strength, while pore design with significant dendrites provides the worst tradeoff between heat transfer performance and flow resistance.

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Section: Resultsmentioning

confidence: 75%

Section: Passive Characterizationmentioning

confidence: 90%

Section: Regenerator Preparation and Geometric Characterizationmentioning

confidence: 99%

Section: Regenerator Preparation and Geometric Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization of Freeze-Cast Micro-Channel Monoliths as Active and Passive Regenerators

et al. 2020

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Caloric devices: A review on numerical modeling and optimization strategies

2021

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Summary The discovery of giant caloric effects and further investigation on device systems that can compete with current heat management technologies in terms of efficiency have led to a major increase in modeling investigations. These models have been crucial in designing the most efficient, cheap, and robust setups with reliable performances. One example is the modeling of magnetic refrigerators and heat pumps that has been used in the optimization of critical geometrical parameters of magnetocaloric regenerators. In this paper, we review the model components of caloric heat pump and refrigerator systems, including field generation, heat transfer, caloric effects, fluid dynamics, and loss mechanisms. We also review the optimization strategies used so far, which are based on sensitive analysis, brute force approaches, statistical learning, and genetic algorithms. The analysis is applied to magnetocaloric, electrocaloric, elastocaloric, and barocaloric systems.

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