Solar Hot Water Technology And Heat Exchangers

By Author: James
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In designing a solar heating installation, the entire circuit must be tuned to the specific application and location. Some solar hot water systems have been designed for residential use, providing a household with solar thermal energy for the requirements of washing, cleaning, air conditioning, dehumidification, and not least of all, heating. Solar hot water installations can be used, for buildings larger than the average family home, such as for space heating. Office buildings, warehouses, factories and stores can all benefit from the cost effective use of solar energy for solar heating. Other uses of solar hot water can be found within industry; this energy is able to be used for process heat in a wide variety of applications from beverage making to material sciences.
There is a need for transfer the heat energy between materials and over distances within each solar solar hot water installation. An essential part of this variety of solar power system is the heat exchanger. Heat exchangers are a specific device designed to transfer energy from one medium to another, usually two fluids. Some options for fluids in solar ...
... thermal energy include water, variations on glycol (propylene glycol, tetraethylene glycol and diethylene glycol), and diphenyl mixtures. The Solarbeam Concentrator is a revolutionary two-axis parabolic concentrator that uses food-grade propylene glycol as the heat transfer fluid in the solar heating circuit. As such, any spills or accidents involving the food-grade propylene glycol are nigh inconsequential; it is a harmless fluid for humans.
Options also exist for the style and build of heat exchanger. These must be chosen carefully for each solar hot water system. The system designer must consider many variables such as pressure limits and differentials, exchange products, fluid flow, location and maintenance as well as thermal performance. A few styles of heat exchanger appropriate for solar energy applications are listed below.
Tubular heat exchangers involve one fluid flowing within tubes, and the other fluid in direct contact with the outside of these tubes. This all takes place within an enclosure, either a larger tube or a shell. Tubes may either be plain or finned. Finned tube heat exchangers have more surface area available within an enclosure, however plain tubes have more energy transmission per unit area. This choice is usually governed by size constraints in the solar hot water system.
Plate heat exchangers are compact and efficient. Metal plates are welded together with piping at each corner. There are cold and hot channels, allowing each liquid to pass through the plate system. Each plate either heats or cools the fluids, thus enabling for heat exchange. With this design, there is a high pressure drop across the system. Therefore pumping must be considered for the solar hot water setup. As well, one must ensure the gasket and sealing quality is up to par, as these are the stress points in the design.
Phase change heat exchangers make direct use of the thermochemical properties of certain elements. Heat is stored and exchanged through the phase change reaction. A Phase Change Material (PCM) must be involved in the design. The PCM can be encapsulated in a more stable material (either plastic or metal, depending on the temperatures). Then the PCM is allowed to come in contact with another material, for heating or cooling. A common example of a phase change material is water, as heat can be transferred through evaporation and condensation. However, higher temperature applications within solar thermal energy make use of certain Magnesium, Calcium and Sulfur materials for this process.

There exist many options for heat exchangers today. The Solarbeam Concentrator is compatible with any type of heat exchanger on the market. It is a very versatile system that can be used in nearly any situation requiring solar thermal energy. The Solarbeam is sold throughout the world by licensed and qualified distributors.
Written by: Joel Smith

This is a guest post by James Peter. He is a fairly well-known solar hot water and Solarbeam Concentrator.