Solar Water Heater

Abstract

A solar water heating apparatus comprising inner and outer concentrically arranged vessels; a cavity defined between the vessels by an outer wall of the inner vessel and an inner wall of the outer vessel; a liquid-to-vapour phase change material provided in the cavity; an inlet for delivering unhealed water to the Inner vessel; and an outlet or withdrawing heated water from the inner vessel, and a pump which pumps the phase change material towards the inner wall of the outer vessel.

Description

FIELD OF THE INVENTION[0001]The present invention is concerned with a solar water heater, and preferably, but not exclusively, a solar water heated which is intended to be retrofitted to an existing domestic hot water supply system or the like, in order to reduce the energy requirements of such a system.BACKGROUND OF THE INVENTION[0002]Conventional solar water heating systems generally comprise a separate solar collector and water store, with pipes connecting the collector(s) to and from store(s). These systems can be either active or passive, with the active systems using an electric pump, and the passive systems relying on buoyancy forces in the form of thermosiphonic action. The collector can be anything from a simple flat plate arrangement requiring freeze protection, to the more costly evacuated (heat pipe) tube system. The collector is generally connected indirectly to the existing hot water installation, and as such, requires a twin coil hot water cylinder.[0003]While solar w...

AI Technical Summary

Benefits of technology

The patent text describes a solar water heating system that uses a cavity containing a liquid-to-vapor phase change material. The system includes inner and outer vessels, with fins on the outer vessel to promote heat transfer. The system also includes a pump to produce a film of phase change material that enhances heat transfer and evaporation. Additionally, a reservoir can be included within the cavity to improve heat transfer and evaporation. A divider can also be included to reduce vapor heat transfer losses through the upper end of the outer vessel. These technical effects improve the efficiency and effectiveness of solar water heating systems.

Problems solved by technology

While solar water heating systems are very effective in some environments, in a large number of countries or regions of the world, a combination of low average daily insolation (incident solar radiation) levels and the need for freeze protection measures render commercially available domestic solar water heating systems unsuitable or prohibitively expensive.

Current systems suffer substantial heat loss during periods of low insolation and / or night-time via the large exposed aperture area, reducing the unit's efficiency and rendering it less attractive to potential users.

However, the integrated unit has a significant problem due to its unique mode of operation.

The earliest systems suffered substantially from heat losses to ambient, especially at night-time and during non-collection periods.

This meant that no matter how effective the unit was in collecting solar energy, unless the hot water was fully withdrawn at the end of the collection period, losses to ambient led to only lukewarm water being available early the next day.

This reduced the overall solar fraction, rendering it less viable economically.

Indeed, this deficiency in the late nineteenth century led to the prominence of thermossiphonic solar water heaters with diurnal heat storage to the detriment of the ICSSWH system.

The ICSSWH is a common form of water heater in many warmer countries, however, it is virtually non-existent in more northern latitudes.

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