A Review of Phase Change Materials used in Solar Water Heaters’ Storage System

2020 ◽  
Vol 7 (11) ◽  
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Storage System ◽  
Solar Water ◽  
Water Heaters ◽  
Materials Used ◽  
Solar Water Heaters

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

2017 ◽  
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.

Solar Thermal Collector With Multifunctional Absorber Layers

2017 ◽  
Author(s):  
Sarvenaz Sobhansarbandi ◽  
Patricia M. Martinez ◽  
Alexios Papadimitratos ◽  
Anvar Zakhidov ◽  
Fatemeh Hassanipour
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Phase Change ◽  
Phase Change Materials ◽  
Black Body ◽  
Heat Accumulation ◽  
Water Heater ◽  
Solar Water ◽  
Water Heaters ◽  
Solar Water Heaters

Solar water heaters (SWHs) are a well-established renewable energy technology that have been widely adopted around the world. In this study we have significantly improved the Evacuated Tube solar Collectors (ETCs) by utilizing the “dry-drawable” Carbon Nanotube (CNT) sheet coatings to increase the solar energy absorption and Phase Change Materials (PCMs) to increase the heat accumulation for application in solar water heaters. The proposed solar collector utilizes a phase change material namely Octadecane paraffin, with melting temperatures of 28°C which is categorized as non-toxic with long-term chemical stability PCM. As PCMs particularly in powder form may not be effective by itself due to the poor heat transfer rate, low thermal diffusivity and thermal conductivity, by combining CNT layers with the high thermal diffusivity and thermal conductivity compare to phase change materials, we are able to overcome the shortcomings of PCMs and design an innovative and efficient solar water heater. With the current technology, we can provide a near ideal black body surface, absorbing a maximum of 98%, between 600–1100 nm, of solar light striking the surface, and providing additional spectral absorption which improves the performance of the solar heater. Applying CNT sheets in conjunction with PCM enables heat storage directly on the collector for a more constant output, even on a cloudy day and prolonged output of heat at night.

Preparation and Evaluation of PCMs by Macro Encapsulation for Solar Energy Storage

2021 ◽  
Vol 14 ◽  
Author(s):  
Sunita Routray ◽  
Vishal Agarwal ◽  
Ranjita Swain ◽  
Rudra Narayan Mohapatro
Keyword(s):  
Phase Change ◽  
Large Scale ◽  
Phase Change Materials ◽  
Low Cost ◽  
Storage System ◽  
Solar Water Heater ◽  
Water Heater ◽  
Latent Heat Storage ◽  
Solar Water ◽  
Thermal Fluids

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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