US2757521A - Gas cycle heat pump - Google Patents

Description

GAS CYCLE HEAT PUMP Alec Raymond Bennett, Moseley, Birmingham, England, assignor to Radiation Limited, LondomEngIand, a British company i Application April 30, 1954, Serial No. 426,796

2 Claims. (Cl. 62-136) The object of the present invention is to provide a heat pump or/and a refrigerator in a simple and compact form, and adapted more particularly for room or other space warming or cooling.

A heat pump or refrigerator in accordance with the invention comprises the combination of a hollow rotor within the interior of which the working uid, which may be air or other gas or vapour, can circulate between the central and peripheral parts of the rotor, and an axial duct through the centre of the rotor for conveying a stream of air, water or other iluid serving as a low grade heat source, the arrangement being such that by rotation of the rotor the working lluid is alternately compressed and expanded, with consequent heating and cooling, and makes thermal contact with the low grade heat source when in the expanded condition, heat being given up to the medium to be heated while the working fluid is in the compressed condition.

The accompanying drawing is a half-sectional side elevation of an apparatus embodying the invention.

Referring to the drawing the hollow rotor is of substantially cylindrical form and is rotatable about its horizontal axis at a high speed by any convenient means. In the example shown in the drawing the rotor is driven by a belt through the pulley a but it may be driven directly by a turbine or other high speed power source, or through gearing. The particular rotor illustrated consists of two relatively rotatable parts, but for explanatory purposes, it will, for the present be assumed that it consists of a single part, the use of this alone being satisfactory in some conditions. The additional part, though optional is desirable for the reason to be hereinafter described. The rotor in its simplest form comprises an inner tube b which surrounds a fixed axial pipe c. On the latter are secured longitudinal heat conducting ns d. To the ends of the tube b are secured hollow impellers e, f having therein appropriately shaped passages through which the working lluid can ow in the directions indicated by the arrows. The impellers are made of tapering form as shown, the widest part being at the central region. The peripheries of the impellers are interconnected by cylindrical and concentric shells g, h forming an annular passage The part h is made from thin metal of good thermal conductivity. The part g may be of low-conductivity material. The impellers may be made from metal in which case they are lagged `by a covering material of low thermal conductivity such as glass fibers, or they may be constructed from any suitable material of low thermal conductivity. The tube b is thermally insulated by a lagging i of glass bres or the like which is held in position by a tube k. Motion is transmitted to the rotor from the pulley a or other source through a sleeve m secured to the impeller f. The fixed pipe c is a duct for conveying a stream of lluid serving as the low grade heat source. This liuid may be, for example, air, water, or brine.

In the construction illustrated the rotor is supported on the pipe c by bearings o. To effect the required cirnited States Patent() 2,757,521 Patented Aug. 7, 1956 ICC culation of the working fluid within the rotor, there is contained in the tube b at a position adjacent to the impeller e an axial-flow fan p which rotates with the rotor.

As the working fluid is flung outwards by centrifugal force, there tends to be formed at the centre a partial vacuum. To retain the full eiciency of the fan and maintain high heat transfer to the central tube it is advantageous to have as high a gaseous density there as possible. There are, however, practical diiculties in pressurizing the rotor and therefore vents communicating with the atmosphere are provided to allow ingress of air on starting and egress on stopping.

In the example illustrated, the rotor is contained in a housing comprising end walls q and a cylindrical peripheral part r. The housing is provided with an air inlet s and outlet t for connection to pipes forming a circulatory system through which heated air derived :from the rotor can flow from and to the housing. Whilst for most purposes the housing is desirable, it is not essential, as an exposed rotor may be used for transmitting heat directly, to for example, the air of a room to be warmed.

The mode of action is as follows:

When the rotor is spun about its axis at a high speed, for example, about 10,000 revolutions per minute, centrif ugal force causes a higher pressure at the periphery than at the centre. Concurrently the contained working uid is circulated around the passages by the fan. In this circulation the lluid goes through the following cycle of operations, viz:

(l) a compression in the impeller e and consequent rise of temperature as the fluid moves outwards;

(Z) rejection of heat at constant pressure as the lluid moves along the annular passage i;

(3) expansion and performance of work with consequent fall of temperature as the fluid moves inwards through the impeller f;

(4) absorption of heat at constant pressure as the fluid moves along the central passage.

Heat at a low temperature is thus taken from air, water or brine passing through the central pipe c and heat at a higher temperature is transmitted through the outer periphery of the rotor to the space-warming air in the housing.

As already mentioned, air or other gas or other gas or vapour may be used as the working medium. Alter natively any convenient low pressure gaseous and liquifiable refrigerant may be used, so as to obtain advantages associated with a liquid, as for example, its latent heat and its higher heat transfer coeflicient.

By this invention a heat pump for such a purpose as that above mentioned is provided in a very simple form. But the apparatus may be used either for heating or for refrigerating purposes or both. When refrigeration is required the liquid in the central pipe is caused to circulate through any appropriate pipe or other system.

The invention is not, however, restricted to the example described, as the constructional details may be varied to suit different requirements. Further, and as already stated, the rotor may be constructed in 'the alternative form shown in the drawing.

It will readily be appreciated that a rotor rotating at high speed may encounter a large resistance from the air in contact with more particularly the cylindrical periphery of the rotor, this being attributable at least in part to turbulence in the air. As a consequence a correspondingly high power is required for actuating the rotor. To minimise this condition, it has been found advantageous to construct the rotor from at least two relatively rotatable parts having a narrow annular space be tween them. In the example illustrated one of the rotor parts consists of the part already described, and which alone is suiciently satisfactory for some purposes. This part lies within an additional part which comprises end walls v and a cylindrical peripheral part w. The additional part is independently supported on bearings x, and is freely rotatable at a slower speed than the driven part by the drag of the air contained between the parts. Further the annular space between the peripheries of the two parts is made as narrow asis convenient. By this expedient wastage of the driving power exerted on the inner part by turbulence in the adjacent air can be substantially reduced.

When a two-part rotor is employed as above described, the construction can be simplified by omitting the cylindrical part h, or both this part and the part g, though this may involve some loss of efficiency as regards the power required to drive the rotor.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A thermodynamic machinev comprising in combination a hollow rotor provided internally with radially disposed annular passages interconnected by inner and outer peripheral annular passages which form with the radially disposed annular passages a closed circulatory path through which a working uid can circulate within the rotor, and can be alternately compressed and expanded with consequent heating and cooling, when the rotor is in action, so that the working tiuid, when in the compressed condition gives up heat around the outer periphery of the rotor, a duct extending axially through the rotor, and arranged in thermal contact therewith so that heat transfer can take place between the working iuid and another fluid owing through the duct, and a circulatory fan for the working fluid situated in the rotor at a position adjacent to the duct, and operatively connected to the rotor.

2. A thermodynamic machine according to claim 1, in which the rotor comprises a positively driven inner part, and at least one separately rotatable outer part arranged concentrically with the inner part, and driven by the drag of the air rotated by the inner part.

References Cited in the tile of this patent UNITED STATES PATENTS 2,451,873 Roebuck Oct. 19, 1948 2,490,064 Kollsman Dec. 6, 1949 2,490,065 Kollsman Dec. 6, 1949 2,520,729 Kollsman Aug. 29, 1950 2,602,306 Japolsky July 8, 1952

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