Refrigeration – Refrigeration producer – Compressor-condenser-evaporator circuit
Reexamination Certificate
1999-08-26
2001-03-27
McDermott, Corrine (Department: 3744)
Refrigeration
Refrigeration producer
Compressor-condenser-evaporator circuit
C062S185000, C062S201000, C062S325000, C062S430000, C062S435000
Reexamination Certificate
active
06205811
ABSTRACT:
The present invention relates to a device for modifying the temperature of a working medium.
There is a requirement, in industry, to impart a moderate temperature, that is to say of the order of magnitude of ambient temperatures, to a working medium. The need is, for example, for maintaining a liquid or gaseous working medium at a defined temperature, even though this medium is otherwise participating elsewhere in at least one procedure that tends to move it away from this required temperature. Such situations are encountered, for example, in the context of agricultural food production or even in the case of air-conditioning mediums, for example within compartments enclosing electrical or electronic installations. It is often possible to carry out the regulation in a very economical way as far as energy is concerned by thermal exchange with the atmosphere by means of a device known as an “air-cooler” tower. However, the temperature of the atmosphere varies very greatly depending on climatic conditions. In the frequent situation where it is necessary to cool the working medium, this is no longer possible when the ambient temperature is higher than the set temperature. Likewise, in an application where the working medium might need to be heated up, this is no longer possible when the atmospheric temperature is below the set temperature. In order to remedy this drawback, it is known to cool the air by evaporating off some of the working medium (water, in general) or an ancillary medium before carrying out the thermal exchange by convection between the air and working medium. This method is space-consuming, produces a plume of vapor and mineral deposits in the apparatus. When it is the working medium that is evaporated, it therefore circulates in an open circuit, with risks of bacterial contamination and of fouling.
It is also known to have the working medium pass along another exchange path where the working medium is subjected to the action of a refrigeration unit. The refrigeration unit is put into operation only when the atmospheric temperature is inappropriate for allowing the thermal exchange between the working medium and the ambient air to bring the working medium to the set temperature. However, this solution increases the losses of pressure head and the risks of leakage affecting the working medium circuit. In order to reduce the losses of pressure head, a valve may be provided to bypass the refrigeration exchanger when the refrigeration circuit is out of use, but that further increases the structural and control complexity, as well as the risks of leakage.
A device is known, furthermore, from EP-A-0 143 855, in which the working medium is incoming air which is reheated by the heat recovered from the outgoing air, via a transfer medium. In order to supplement the heat imparted to the incoming air, the transfer medium, on its path towards the exchanger with the incoming air, takes heat from the condenser of a refrigeration machine and, on its return path back to the exchanger with the outgoing air, is re-cooled by contact with the evaporator of the same refrigeration machine. Such a machine here again has the aim of thermal optimization but at the expense of great technical complexity.
The aim of the present invention is to remedy these drawbacks by proposing a device that makes it possible to modify the temperature of a working medium, which is at the same time less space-consuming, more economical and more reliable than the known devices.
According to the invention, a device for modifying the temperature of a working medium, comprising:
a first heat exchange path traversed by the working medium and installed in a thermal exchange relationship with a transfer path traversed by a transfer medium; and
a refrigeration circuit comprising a second and a third heat-exchange path for a refrigeration medium, one having a function of heat absorption by the refrigeration circuit and the other a function of heat release by the refrigeration circuit, at least at certain stages of operation,
one of the second and third exchange paths being installed in a thermal exchange relationship with the transfer path upstream of the first exchange path, in such a way that the temperature of the transfer medium is modified by heat exchange with the refrigeration medium before the thermal exchange between the transfer medium and the working medium traversing the first exchange path,
is characterized in that the transfer path is an open path having, upstream of the exchange paths, an inlet path in which the temperature conditions are substantially independent of the conditions of operation of the device.
Particularly when the temperature of the incoming transfer medium, such as ambient air, is inappropriate for the exchange with the transfer medium to bring the working medium to the desired temperature, the temperature of the transfer medium is first modified by virtue of the refrigeration circuit.
Hence a simple, compact and particularly reliable construction is achieved, particularly as regards risks of leakage, fouling and bacterial contamination. The man skilled in the art is led away from the solution according to the present invention because the efficiency of thermal exchange between the working medium and the refrigeration medium via the transfer medium is unfavorable by reason of the multiple interfaces between these mediums. However, it has been found according to the present invention that this drawback is more than compensated by the advantages set out above, particularly in the preferred applications where the refrigeration circuit is put into operation only in cases of relatively infrequent climatic conditions.
The construction according to the present invention is fundamentally distinguished from that according to
EP 0 143 855 where the transfer medium circulates in closed loop and where the refrigeration machine has the essential function of creating a difference between the average temperature in the exchanger with the incoming air and that in the exchanger for recovering heat from the outgoing air.
Preferably, at least one of the inlet and outlet paths can be connected to a store of transfer medium belonging to the environment.
The transfer medium is preferably atmospheric air or the ambient air of the premises. It may also be seawater, lake water, river water or pond water, or even a waste medium such as fumes.
Typically, the input temperature of the transfer medium is not controlled or is poorly controlled, and little or no concern is devoted to the temperature at which the transfer medium is expelled at the other end of the transfer path.
Preferably, the first exchange path is installed in the transfer path in series between the second and the third exchange paths.
Hence, the three exchange paths, consisting for example of banks of tubes, are situated one after the other on the same path of a transfer medium which may be air taken up from the external atmosphere, the internal atmosphere of the premises, seawater, lake or river water, etc. This transfer medium is first cooled by the evaporator of the refrigeration unit, then heated by the first exchange path which is that traveled by the working medium, then again further heated by the condenser of the refrigeration unit. The observation which is the basis of this embodiment of the invention is that the temperature of the transfer medium after being heated up by the first exchange path is approximately the same as that of the atmospheric air or other transfer medium entering the device according to the present invention. Hence, the condenser undergoes the same cooling effect from the transfer medium as if a separate flow of transfer medium were impinging directly on the condenser. This version of the invention thus makes it possible to dispense with a second transfer medium path, with a means such as a motor-driven fan for impelling the transfer medium in this second transfer path, as well as with the energy for operating this motor-driven fan. Moreover, as the three thermal exchange paths may be mounted one behind the other o
Greer Burns & Crain Ltd
McDermott Corrine
Norman Marc
TEFA
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