• Ouaouja, Z., Havet, M., Rouaud, O., Toublanc, C., & Ousegui, A. (2025). Thermal properties and performance of glycerol-water-NaCl phase change material for cold chain applications. Journal of Energy Storage, 126, 117045. DOI: 10.1016/j.est.2025.117045

Abstract:

This study investigates the thermal properties of glycerol-water mixtures and their potential as Phase Change Materials (PCMs) for Cold Thermal Energy Storage (CTES) in cold chain applications. The study characterizes key thermal properties, including Phase Change Temperature (PCT), latent heat, density, thermal conductivity, and specific heat. Results indicated that increasing glycerol concentration decreased the PCT of the mixture, reaching -7.76°C to -21.82°C, at glycerol concentrations ranging between 25 wt.% to 45 wt.%, respectively. However, this decrease in PCT is accompanied by a reduction in latent heat, 147.5 kJ·kg-1 to 73.6 kJ·kg-1 for the respective concentrations.

To enhance the PCM properties and achieve optimal thermal performance, NaCl was added as an additive to the glycerol-water mixture. The Response Surface Methodology (RSM) was employed to optimize the concentrations of PCM components, aiming to achieve a desired PCT of -20°C and maximize latent heat capacity. The developed model demonstrated high predictability, with an R² of 99.20%, and good statistical significance, as indicated by an overall model F-value of 98.68 and a P-value of 0.0003. Based on this optimization, three mixtures were selected for further characterization, exhibiting suitable PCT values of around -20 °C to -18°C and latent heat capacities ranging from 97 kJ·kg-1 (PCM M1) to 280 kJ·kg-1 (PCM M3).

A one-dimensional model was developed to assess the impact of optimized PCM M3 on the temperature stability of frozen food products. Incorporating the PCM layers significantly improved the thermal control of the perishable product. During standard freezer operation, the product temperature was maintained at -20°C±0.065°C compared to the reference case (without PCM) at  20 ±0.81°C. During defrost cycles, and using PCM M3, the maximum product temperature reached -19.42°C, compared to -16.98°C without PCM.

Keywords:

Phase Change Materials; Cold Thermal Energy Storage; Cold Chain; Latent Heat; Thermophysical Characterization; Glycerol; Numerical Mode

Graphical Abstract

• Ouaouja, Z., & Ousegui, A. (2024). Inverse Method for Estimating Thermal Properties of Phase Change Material Using Levenberg-Marquardt Method. 2024 4th International Conference on Innovative Research in Applied Science, Engineering and Technology (IRASET), 1–7. DOI: 10.1109/IRASET60544.2024.10548938

Abstract:

This paper investigates the application of the Inverse method to a 1-D semi-infinite melting problem in order to estimate thermal properties of of Phase Change Material (PCM), including the melting point, density, and latent heat capacity. The problem predicts temperature using an analytical solution based on Stefan's problem that uses Neumann's similarity solution. It then estimates the unknown parameters using nonlinear inverse method based on the Levenberg-Marquardt Optimization (LMO). Two PCMs, sodium sulfate and water, were used to validate and evaluate the efficiency of the proposed model. Numerical results show that the model is robust as it converges quickly to exact values - 34 iterations for sodium sulfate case and 22 for water - indicating high reliability with negliglble error.

Keywords:

Inverse Heat Transfer; Stefan Problem; Inverse Method; Levenberg-Marquardt Method; Phase Change Materials

Graphical Abstract