Electric resistance heating devices – Heating devices – Continuous flow type fluid heater
Reexamination Certificate
1999-06-03
2001-05-22
Walberg, Teresa (Department: 3742)
Electric resistance heating devices
Heating devices
Continuous flow type fluid heater
C392S483000, C392S488000
Reexamination Certificate
active
06236810
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a fluid temperature control device, and more particularly to an improved construction for cooling a fluid.
BACKGROUND ART
A circulating fluid is often used to control the temperature of a processing chamber or walls of a device, such as an constant-temperature tank, semiconductor manufacturing device (etching device or CVD device for example), or plastic plate thermocompression molder. In Japanese Patent Laid-open No. 7-280470 and Japanese Patent Laid-open No. 7-308592 are disclosed devices suitable for controlling the temperature of a circulating fluid.
The device disclosed in Japanese Patent Laid-open No. 7-280470 has an electric heater inserted into a pipe in which is flowing a fluid; covering the outside surface of this pipe is an even larger pipe, and cooling water is made to flow between the outside pipe and inside pipe. The electric heater and the cooling water are used to control the temperature of the fluid.
The device disclosed in Japanese Patent Laid-open No. 7-308592 has a radiator joined via a thermoelectric conversion element to a heat transfer block, on the inside of which is made to flow a fluid. The fluid flowing in the block is cooled or heated by the thermoelectric conversion element. The heat absorbed by the thermoelectric conversion element from the fluid is discharged to the atmosphere by a radiator.
The above-mentioned conventional fluid temperature control devices have the following disadvantages, in particular as relates to cooling performance.
The device in Japanese Patent Laid-open No. 7-280470 cannot cool the fluid below the temperature of the cooling liquid, which means it has a narrow cooling temperature range. Further, in general, it is difficult to make fine adjustments to the cooling liquid temperature or flow volume, so if the fluid temperature is not finely adjusted by also using a heater during cooling, then the fluid cannot be cooled to the target temperature with good accuracy.
The device of Japanese Patent Laid-open No. 7-308592 discharges heat to the atmosphere from a thermoelectric conversion element during cooling, but the low heat capacity of the atmosphere causes the cooling capacity to be low, which means it is difficult to process a large quantity of fluid in a short time. Further, because the thermoelectric conversion element is used for both heating and cooling, the controllable temperature range is not very wide and the life of the thermoelectric conversion element is shortened.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a fluid temperature control device with high cooling capacity, wide controllable temperature range, and excellent temperature control accuracy.
An additional object of the present invention is to provide a fluid temperature control device with simple cooling amount control.
In accordance with a first aspect of the present invention, the fluid temperature control device comprises a fluid passage in which flows a fluid, a cooling liquid passage in which flows a cooling liquid, and thermoelectric conversion elements situated between the fluid passage and the cooling liquid passage so as to allow heat to be absorbed from the fluid and heat to be discharged to the cooling liquid.
By placing the thermoelectric conversion elements between the fluid passage and the cooling liquid passage to effect absorption of heat from the fluid and discharge of heat to the cooling liquid, the fluid temperature control device affords larger cooling capacity than conventional devices, which performs cooling by means of the cooling liquid alone or discharge heat from the thermoelectric conversion elements to the atmosphere, and allows the fluid to be cooled to a temperature below the temperature of the cooling liquid. Further, the thermoelectric conversion elements not only increase the amount of cooling but can also act to suppress the amount of cooling by the cooling liquid to allow fine control of the amount of cooling, which is difficult to achieve using just a cooling liquid.
It is desirable that the fluid temperature control device further comprise a heater that is placed in the proximity of the fluid passage. It is desirable that the heater be a lamp that emits infrared light. This makes it possible to effect heating and cooling of the fluid over a wide temperature range.
In a preferred embodiment, there is a cylindrical vessel and along the outside surface of this vessel are placed thermoelectric conversion elements. A transparent cylinder is inserted into the vessel, and the space between the outside surface of the transparent cylinder and the inside surface of the vessel forms the fluid passage. Into the transparent cylinder is inserted an infrared light emitting lamp that acts as a heater. The thermoelectric conversion elements can be joined to the outside surface of the vessel or can be embedded in the wall of the vessel. The thermoelectric conversion elements are placed over substantially the entire outside surface area of the vessel. On the exterior of the thermoelectric conversion elements is placed a cooling liquid passage. The cooling liquid passage can be formed by joining to the thermoelectric conversion elements the tubes in which flows the cooling liquid, or by fitting a larger diameter outer cylinder about the exterior of the vessel so that the space between the inside surface of the outer cylinder and the outside surface of the vessel or the outside surfaces of the thermoelectric conversion elements forms a cooling liquid passage. Further, a large number of fins are placed in the fluid passage and the cooling liquid passage.
Water or refrigerant from a refrigeration circuit can be used as the cooling liquid in the cooling liquid passage of the fluid temperature control device of the present invention. Alternatively, anti-freeze can be cooled by a refrigeration circuit and then made to flow in the cooling liquid passage.
In accordance with a second aspect of the present invention, the fluid temperature control device comprises a cylindrical vessel having a fluid passage along its inner surface and thermoelectric conversion elements placed on the wall of the vessel for absorbing heat from the fluid.
Because the fluid temperature control device allows the thermoelectric conversion elements to be placed on the wall of the cylindrical vessel so as to surround the fluid passage, a cooling capacity that is high given the size of the device can be achieved, as can a wide cooling temperature range. Further, by allowing the amount of cooling to be controlled by the thermoelectric conversion elements while also allowing nearly uniform cooling of the fluid in the fluid passage, there is provided high accuracy of temperature control.
It is desirable that the fluid temperature control device further comprise a cooling liquid passage placed in proximity to the thermoelectric conversion element in order to absorb the heat discharged from the thermoelectric conversion element. This significantly increases the cooling capacity. Further, it is desirable that the fluid temperature control device further comprise a heater, situated in proximity to the fluid passage, for heating the fluid.
If the wall of the cylindrical vessel is sufficiently thick, a plurality of holes or hollows can be placed in the wall. This will reduce the volume of the cylinder, making it lighter, and will reduce the heat capacity of the cylinder, improving the thermal response of the device. It is desirable that the shape and position of the holes or hollows be selected such that the areas of the cylinder wall without holes or hollows will extend continuously along a heat transmission path from the vessel interior side fluid passage to the thermoelectric conversion elements. This will allow almost no degradation of the vessel's heat transmission even when there are holes or hollows in the vessel.
REFERENCES:
patent: 3108174 (1963-10-01), Hynes
patent: 3334400 (1967-08-01), Jaeger
patent: 3777117 (1973-12-01), Othmer
patent: 4083478 (1978-04-01), McLane
patent: 4514617 (198
Dahbour Fadi H.
Gallagher & Lathrop
Komatsu Ltd.
Lathrop David N.
Walberg Teresa
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