Refrigeration – Using electrical or magnetic effect – Thermoelectric; e.g. – peltier effect
Patent
1993-07-07
1996-08-13
Sollecito, John M.
Refrigeration
Using electrical or magnetic effect
Thermoelectric; e.g., peltier effect
62 33, 62 32, 165170, F25B 2102
Patent
active
055444873
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to thermoelectric refrigeration systems.
FIELD OF THE INVENTION
It is known to use thermoelectric modules in refrigeration systems. A thermoelectric module is a known type of heat pump in which the passage of an electric current through the module causes one side of the module to be cooled and the opposite side of the module to be heated. Thermoelectric modules are also known as Peltier modules or thermoelectric heat pumps.
Previously known refrigeration units containing thermoelectric modules have comprised aluminium heat sinks which are clamped tightly to each side of the thermoelectric module, creating a thermoelectric assembly. When an electric current is applied to the module, heat is pumped from one side to the other side. Initially, when a current is first applied to the thermoelectric module the temperature differential between the two side is at a minimum. Under these conditions the thermoelectric assembly offers efficient performance. However, as the refrigerator approaches its desired internal temperature here is an increased temperature difference between the two sides. Under these conditions the thermoelectric assembly becomes less efficient as a heat pump. When the thermoelectric module is configured as a heat pump a conventional thermoelectric assembly must always have an electric current applied to it in order maintain a temperature differential across the device. If this current is removed then heat will flow through the assembly in such a manner as to re-establish thermal equilibrium. Therefore, in practice, conventional thermoelectric assemblies consume power simply to maintain a temperature difference across the assembly. This is very wasteful of energy.
In practice, conventional thermoelectric assemblies also suffer from the effects of thermal impedances which occur at the boundaries of the thermoelectric module and the heat sinks. This requires great care and expense in the manufacture of thermoelectric assemblies to ensure the minimisation of these boundary effects.
Some thermoelectric assemblies have two small thermoelectric modules sandwiched between heat sinks rather than a single thermoelectric module in an effort to try and increase the surface area contact with the heat sinks. However, the structural and design limitations of thermoelectric modules forced on them by the clamping forces of solid heat sinks and cost, restrict the modules themselves to being necessarily small, clearly preventing large-area thermal contact.
Also, for the sac reasons, electrical connectors between P & N thermocouples within thermoelectric modules are very small. This is restrictive as improved performance can be achieved by utilising greater thermal area contact via large thermal connections.
Another major limiting factor in conventional thermoelectric module design is the fact that the hot and cold faces of the modules are close together (usually within 5 mm). There are very significant losses through convection, conduction and radiation from one face to another i.e. high heat transfer. This greatly limits the ultimate performance of the thermoelectric modules. Exacerbating this problem even further in conventional thermoelectric assemblies is the fact that the solid heat sinks attached to the module faces are In close proximity to one another. The thermal mass and close proximity of the two heat sinks in a conventional thermoelectric assembly constantly work against one another. The abovementioned problems have restricted the use of thermoelectric assemblies to very small, portable coolers and refrigerators. Thermoelectric assemblies have hoe been practical for use in domestic refrigeration because of, for example, the high power consumption.
SUMMARY OF THE INVENTION
The present invention provides thermoelectric systems suitable for use in refrigeration in which at least some of the problems of the prior art are alleviated. In accordance with one aspect of the present invention there is provided a thermoelectric system characterised by comprising a
REFERENCES:
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patent: 3295667 (1965-09-01), Frantti
patent: 3481393 (1969-12-01), Chu
patent: 4109707 (1978-08-01), Wilson et al.
patent: 4829771 (1989-05-01), Koslow et al.
patent: 5154661 (1992-10-01), Higgins
Attey Graeme S.
Sargeant Gary L.
Searls Jesse H.
Hydrocool Pty Ltd
Sollecito John M.
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