M.J. Huang

Comparison of Predictions Made Using a New 3D Phase Change Material Thermal Control Model with Experimental Measurements and Predictions Made Using a Validated 2D Model

Phase change materials are shown to be an effective means of limiting temperature rise in photovoltaic devices. A three-dimensional (3D) numerical model was developed to simulate the use of a phase change material linked to a PV system to control the temperature rise of the PV cells. The model can be used to predict temperatures, velocity fields, and vortex formation within the system. The predicted temperatures using the 3D model have been compared with experimental measurements for which the system geometry, material characteristics, and boundary conditions have been matched as closely as possible. The 3D predictions have also been compared with those from a previously developed and experimentally validated two-dimensional (2D) finite-volume heat transfer model conjugated hydrodynamically to solve the Navier-Stokes and energy equations. It was found that for the systems simulated with appropriate boundary conditions, the 2D model predictions compare well with those of the 3D model. Using the 3D model, the temperature distributions were predicted when the heat transfer to the PCM was enhanced by high thermal conductivity pin fins. The effects of the container boundaries have been analyzed.

Chapter 454 – The Application of Computational Fluid Dynamics to Predict the Performance of Phase Change Materials for Control of Photovoltaic Cell Temperature in Buildings

Publisher Summary A novel temperature-based numerical simulation model has been developed to predict the thermal performance of phase change materials (PCM) when integrated with photovoltaic (PV). The application of a PCM, to moderate PV cell temperatures and store heat, were investigated with the numerical model. The preliminary results derived from the numerical simulation including the effect on PV, cell temperature of selected PCM material, and dimensions of PCM container are presented. A detailed theoretical analysis of the thermal behavior of paraffin when used to moderate the temperature rise in PV panels and store thermal energy has been undertaken. For the simulated conditions, the temperature of PV can be maintained under 38°C for one and half hours. From the simulations aluminum is a suitable material from which to fabricate the PCM container systems.

Improving the heat retention of integrated collector/storage solar water heaters using Phase Change Materials Slurries

SYNOPSIS Integrated Collector/Storage Solar Water Heaters are very efficient at collecting solar radiation and transferring thermal energy to store during the day in northern latitudes. However the culture and lifestyle in these latitudes tend to require hot water at the beginning of the day and not at the end. The use of phase change materials, and specifically phase change material slurries, as a heat retention material, to hold heat overnight so that it can be used the next day has been investigated. While it was found that with the right concentration of PCM in a carrier fluid a temperature of 50°C could be maintained until 6am the following day, the nature of the slurry material over time disaggregates and quickly becomes unusable.

The Energy Conservation Potential of Using Phase-Change Materials as Thermal Mass Material for Air Source Heat Pump-Driven Underfloor Heating System in a Building

Improved energy efficiency in buildings is the key element to reduce the greenhouse gas emissions while contributing to energy security. Underfloor heating is a more efficient and economical method for home heating with improved thermal comfort than any other heating methods. Due to the low-temperature heating source requirement the underfloor heating is widely accepted as the most efficient form of heating. Heat pumps are energy-efficient equipment to provide low-temperature heat source which is suitable for underfloor heating applications. Phase-change materials (PCMs) are attractive for use in thermal energy store for underfloor heating applications due to their high-energy storage density over a small temperature range, therefore allowing the air source heat pump to operate during winter warmer afternoon ambient air conditions or in an electricity tariff management mode. A numerical simulation model has been validated and used to analyse the thermal performance of PCM-layered underfloor heating under different heating modes. Different layouts of the underfloor heating pipes with PCMs as floor mass material were analysed for realistic diurnal temperature boundary conditions and temperature distribution was predicted.