Refrigeration – Disparate apparatus utilized as heat source or absorber – With vapor compression system
Reexamination Certificate
2002-06-24
2004-03-16
Doerrler, William C. (Department: 3744)
Refrigeration
Disparate apparatus utilized as heat source or absorber
With vapor compression system
C062S323100
Reexamination Certificate
active
06705103
ABSTRACT:
The invention relates to an apparatus for cooling, having a loop carrying a refrigerant, a first heat exchanger for outputting heat to a heat reservoir, a second heat exchanger for extracting heat from a chamber to be cooled, a compressor and an expansion device. The invention also relates to a method for cooling, by means of an apparatus for cooling, having a loop carrying a refrigerant, a first heat exchanger for outputting heat to a heat reservoir, a second heat exchanger for extracting heat from a chamber to be cooled, a compressor and an expansion device, having the steps of operating the compressor and conducting the refrigerant through the loop carrying the refrigerant.
PRIOR ART
Apparatuses and methods of the above generic type are used particularly for climate control in vehicle passenger compartments.
FIG. 3
schematically shows an air conditioner circuit. A first medium enters a first heat exchanger
110
and flows through a loop
160
. The medium gives up heat to the ambient air
162
and thus cools itself down. A cooled medium emerges from the heat exchanger
110
. This cooled medium is now conducted through an inner heat exchanger
128
, whose function will be explained hereinafter. After the medium has emerged from the inner heat exchanger
128
, it enters an expansion device
120
. The medium cools down sharply from expansion and is then delivered to a second heat exchanger
114
. In this heat exchanger
114
, the cold medium can cool down warm ambient air or circulating air and made available, in the form of cold air
164
, to a chamber to be cooled, such as the motor vehicle interior. In this process, the development of condensate
166
occurs. The medium, now evaporated and possibly heated by the heat exchange in the heat exchanger
114
, emerges from the heat exchanger
114
and then flows again through the inner heat exchanger
128
. After emerging from the inner heat exchanger
128
, the medium enters a compressor
118
, where it is heated by compression. Thus a heated medium is again available, which can enter a first heat exchanger
110
for heat exchange. The loop is closed.
The inner heat exchanger
128
serves to increase the power in the loop. Before entering the expansion device
120
, the medium is cooled by the returning medium, which has emerged from the second heat exchanger
114
and is heated in reflux. Higher temperature differences and hence an increase in the efficiency in the loop can thus be achieved.
As the medium in the coolant loop, CO
2
is gaining in significance. The interest in this natural refrigerant is increasing, given the rules and regulations requiring that the use of CFCs be stopped.
Compared to conventional refrigerants, CO
2
has a lower critical temperature of 31.1° C. Above this temperature, liquefaction from a pressure increase is no longer possible. At medium and high ambient temperatures, the heat output therefore occurs at a so-called supercritical pressure, that is, a pressure that for CO
2
is above 73.8 bar. At supercritical pressure, the heat output does not occur by condensation, as in the conventional refrigerants, which occurs at a virtually constant temperature; instead, the pressure and temperature are independent of one another. Gas cooling takes place. However, the states in the evaporator continue to be subcritical. Another notable feature of the behavior of CO
2
is that temperatures of about 140 to 150° C. are already attained in idling.
ADVANTAGES OF THE INVENTION
The invention improves upon the generic apparatus in that a first further heat exchanger is provided, which enables a heat transfer between the loop carrying the refrigerant and a coolant loop. The refrigerant, which can quickly be imparted a high temperature, is thus capable of heating the vehicle coolant. This has numerous advantages. It is already known, to enhance comfort, for the vehicle to be air-conditioned several minutes before a trip begins. For a heated passenger compartment, the air conditioner compressor is operated, so that the refrigerant is compressed. Because once the refrigerant has been compressed before being introduced into the first heat exchanger it is carried into the first further heat exchanger, the coolant can be preheated. In this way, the temperature of the coolant is already at operating temperature even before the internal combustion engine is started. By means of the first further heat exchanger, it is likewise possible for the water located in the radiator to be used at high pressure to cool the refrigerant as needed.
Preferably, the first further heat exchanger is disposed downstream of the compressor in the loop carrying the refrigerant. In this way, the refrigerant is introduced at high temperature into the heat exchanger, so that rapid heating of the coolant in the coolant loop can occur.
It is preferred that the compressor can be operated by a starter/generator or a battery. This starter/generator, which is disconnected from the drive shaft of the engine via a clutch, can thus furnish both the energy for pre-air-conditioning and the energy for heating the coolant before the engine is started.
It is also advantageous that a water pump of the coolant loop can be operated by a starter/generator or a battery. The coolant is thus pumped through the heat exchanger because of the work of the starter/generator.
It is especially advantageous if the first heat exchanger includes a gas cooler. In this way, a heat exchange in the first heat exchanger is not brought about by condensation, as in the conventional refrigerants. Instead, a heat exchange in the gas takes place.
It is especially advantageous if CO
2
is provided as the refrigerant. With CO
2
, the advantages of the invention can be employed especially well, since the CO
2
can be compressed by the compressor to pressures of 100 to 150 bar, using the starter/generator, making it possible to attain temperatures between 140 and 180° C. Rapid heating of the coolant in the coolant loop thus occurs.
It is equally advantageous if a second further heat exchanger is provided between the coolant loop and the motor oil. In this way, the motor oil can be brought to an elevated temperature as well before the engine is started.
In this connection, it can be especially advantageous that a motor oil pump, which can be operated by a starter/generator or a battery, is provided in the motor oil loop. Because of this circumstance, not only the compressor and the water pump but the motor oil pump can also be operated by the starter/generator. It is equally conceivable for a heat exchanger to be placed in the oil sump, that is, in the region of the oil pan, which heat exchanger has coolant flowing through it, so that the heat from the refrigerant is output to the motor oil via the engine coolant. As a heat exchanger, the heat exchanger present in Diesel vehicles between the coolant and the oil can also be used.
There are particular advantages if a third further heat exchanger is provided between the coolant loop and the gear lubricant oil. Thus the gear lubricant oil as well can be brought to temperatures near operating temperatures before the vehicle is put into operation.
It is especially useful if a reversible valve is provided, which can reroute the coolant loop to avoid additional heat flows. This function is useful if no additional heat flows in the coolant during engine operation are wanted. In principle, however, the heat exchanger can also be operated without valves, since the coolant temperatures are below 120° C. The additional heat quantity that is output to the engine coolant by the loop carrying the refrigerant can be output to the ambient air via the coolant heat exchanger. The surface area of the coolant heat exchanger need not be increased for this purpose, since the heat is produced at a higher temperature level. The surface area of the gas cooler for cooling the refrigerant, however, can be reduced, since some of the heat is already output to the coolant before entering the gas cooler.
It is especially advantageous that an inner heat exchanger is provided be
Doerrler William C.
Robert & Bosch GmbH
Striker Michael J.
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