NUMERICAL STUDY OF SOME INFLUENCING PARAMETERS ON MELTING PROCESS OF PHASE CHANGE STORAGE UNITS INTEGRATED WITH A SOLAR WATER HEATER

Abstract: Phase Change Materials (PCMs) are used in a latent heat storage system for storing thermal energy. The thermal conductivity of PCMs is enhanced by macro encapsulation for large-scale use. This technique not only provides a self-supporting structure of PCM, also separates the PCM from thermal fluids and enhances the heat transfer rate. The current work involves the study of encapsulation of low-cost inorganic PCMs, such as Sodium nitrate (NaNO3), in a temperature range of 300 – 500˚C. Silicate coating is also applied to PCM capsules. A Solar water heater is then designed using the macro encapsulated PCM. The water heater consists of copper cylindrical pipes, filled with the phase change material. The efficiency of the solar water heater is found to be 22.5%.

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Evacuated Tube Solar Collectors Integrated With Phase Change Materials and Silicone Oil

Volume 2: I&C, Digital Controls, and Influence of Human Factors; Plant Construction Issues and Supply Chain Management; Plant Operations, Maintenance, Aging Management, Reliability and Performance; Renewable Energy Systems: Solar, Wind, Hydro and Geothermal; Risk Management, Safety and Cyber Security; Steam Turbine-Generators, Electric Generators, Transformers, Switchgear, and Electric BOP and Auxiliaries; Student Competition; Thermal Hydraulics and Computational Fluid Dynamics ◽

10.1115/power-icope2017-3520 ◽

2017 ◽

Cited By ~ 2

Author(s):

Alexios Papadimitratos ◽

Sarvenaz Sobhansarbandi ◽

Vladimir Pozdin ◽

Anvar Zakhidov ◽

Fatemeh Hassanipour

Keyword(s):

Phase Change ◽

Solar Collector ◽

Phase Change Materials ◽

Silicone Oil ◽

Solar Water Heater ◽

Water Heater ◽

Solar Water ◽

Water Heaters ◽

Evacuated Tubes ◽

Solar Water Heaters

This paper presents a novel method of integrating Phase Change Materials (PCMs) and Silicone oil within the Evacuated solar Tube Collectors (ETCs) for application in Solar Water Heaters (SWHs). In this method, heat pipe is immersed inside the phase change material, where heat is effectively accumulated and stored for an extended period of time due to thermal insulation of evacuated tubes. The proposed solar collector utilizes two distinct phase change materials (dual-PCM), namely Tritriacontane paraffin and Erythritol, with melting temperature 72°C and 118°C respectively. The integration of Silicone oil for uniform melting of the PCMs, utilizes the convective heat transfer inside the evacuated tubes, as this liquid polymerized material is well known for its temperature-stability and an excellent heat transfer medium. The operation of solar water heater with the proposed solar collector is investigated during both normal and stagnation (on-demand) operation. The feasibility of this technology is tested via small scale and large scale commercial solar water heaters. Beyond the improved functionality for solar water heater systems, the results from this study show show efficiency improvement of 26% for the normal operation and 66% for the stagnation mode compared with standard solar water heaters that lack phase change materials and silicone oil. The benefit of this method includes improved functionality by delayed release of heat, thus providing hot water during the hours of high demand or when solar intensity is insufficient such in a cloudy day and during night time.

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