Refrigeration – Refrigeration producer – Sorbent type
Reexamination Certificate
2001-03-30
2002-04-30
Bennett, Henry (Department: 3744)
Refrigeration
Refrigeration producer
Sorbent type
C062S457900, C062S476000
Reexamination Certificate
active
06378326
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a sorption cooler for cooling a container by means of a sorption device and a method for regeneration of the sorption agent in accordance with the generic term of claim
1
.
BACKGROUND OF THE INVENTION
Sorption devices are devices in which a liquid or solid sorption agent adsorbs a second, higher boiling agent, the working agent, in vapor form with release of heat (sorption). The working agent is evaporated in an evaporator while taking up heat. After the sorption agent is saturated, it can be desorbed through the delivery of heat (regeneration). In doing so, the working agent is evaporated out of the sorption agent. The work agent vapor can be reliquefied and then reevaporated in the evaporator.
Sorption devices for cooling with solid sorption agents are known from EP 0 368 111 and DE-OS 34 25 419. Sorption agent vessels filled with sorption agents draw off the working agent vapor, which arises in an evaporator, and adsorb it in the sorption agent fill while releasing heat. The heat of adsorption in this case must be withdrawn from the sorption agent fill. The cooling devices can be used for cooling and keeping foods warm in thermally insulated boxes.
The sorption cooling system known from EP 9 368 111 consists of a portable cooling unit and a stationary charging station that can be separated from it. The cooling unit consists of a sorption vessel filled with a solid sorbent and an evaporator, which contains the liquid working agent and a heat exchanger embedded therein. The evaporator and sorption vessel are connected to each other via a closeable vapor pipe. Liquid media that are cooled to the desired temperature level through temperature-controlled opening and closing of the closing device flow through a heat exchanger embedded in the evaporator. After the sorption agent has become saturated with the working agent, it can be heated in the charging station. The working agent vapor that flows out is reliquefied in the evaporator. The heat of condensation is withdrawn through cooling water, which must flow through the embedded heat exchanger.
Because of the embedded heat exchanger and temperature regulation, the sorption cooling system is expensive to manufacture and is complicated in its practical use for the untrained layman.
OBJECTS AND SUMMARY OF THE INVENTION
The task of the invention is to show an operation that is simpler than the prior art and a low-cost device.
This task is solved by the characteristic traits of claims
1
and
10
. The dependent claims show additional inventive devices.
Accordingly, a sorption device in accordance with the invention contains a sorption agent within a sorption agent vessel, a vapor valve and a liquid working agent distributed in a working agent storage material within an evaporator. A portion of the outer wall of the container is in good thermal contact with the working agent storage material and at least this part of the outer wall of the container is at the same time apart of the boundary surface s of the evaporator.
The working agent storage material contains, for example, nonwoven glass fiber or mineral fiber materials and is glued or stretched over a large area. In the case of cylindrical vessels it is, as a rule, sufficient to coat the outer side surface of the container. Coating of the more highly vaulted bottom and top elements is not necessary. The shape of the vessel does not have to be adjusted to the special requirements of sorption technology. The working agent is evaporated out of the working agent storage material and cools the contents of the vessel through the good contact with the vessel wall.
In accordance with the invention another part of the boundary surface of the evaporator has thermal contact with the environment. In this region the working agent vapor can condense and give up its heat of condensation to the environment or to an external cooling medium. This will always take place when the environment or the external cooling medium is colder than the contents of the vessel. The working medium then evaporates from the working medium storage material while absorbing heat and condenses while giving up heat to the environment. Through this effect, which is also known as a heat pipe, the contents of the vessel are constantly reduced to the environmental temperature. However, if the environment is warmer than the contents of the vessel, no heat can be transferred from outside to the inside, provided the boundary surface in contact with the environment is free of liquid working agent. In order to guarantee this, the boundary surface is inclined so that the condensate runs off and can drip back onto the working medium storage material. This heat pipe effect is always of particular advantage when the vessel contents are supposed to take on the lower temperature automatically through a decrease of the ambient temperature. If, for example, the sorption cooler is installed in a cooling chamber, the temperature of the vessel contents will fall to the lower level; conversely, if the outside temperature rises, for example due to solar radiation, the construction of the sorption cooler in accordance with the invention acts like an insulated vessel under a vacuum. In doing so, the rise of the vessel temperature progresses a great deal more slowly than the decrease does.
Even during the regeneration phase, in which the sorption agent is desorbed from the working agent, the working agent vapor can condense on the boundary surface of the evaporator that is in contact with the environment. This always occurs when the boundary surface is colder than the vessel contents.
It is also advantageous if another wall region of the evaporator is at the same time a component of the sorption agent vessel. Weight and costs can be saved through the consolidation of the intermediate walls that is then possible. This is particularly true when the vapor valve is arranged in a common wall. Additional flow channels and connecting elements can then be spared.
Particularly compact and stable embodiments of the idea in accordance with the invention are achieved when the sorption cooler has a shell-like structure. In this case, a cylindrical evaporation jacket is arranged around the cylindrical vessel and around this jacket in turn is the cylindrical sorption vessel, which uses the evaporation jacket simultaneously as its inside wall. In order to reduce the thermal contact between the sorption agent and the evaporator, thermal insulation agents can be arranged within the sorption agent vessel.
However, this additional insulation can be avoided if the working agent vapor pressure is especially low. In the case of low vapor pressures the conductive and convective fractions of heat transfer are reduced. If the zeolite/water pair is used, the achievable insulation effect lies in the range of simple vacuum insulation. The radiant fraction that is still relevant in this case can be further reduced by building in radiation shields. It is particularly advantageous if the common intermediate wall between evaporator and the sorption agent vessel acts as a radiation shield.
During the regeneration phase the sorption agent is heated and the working agent vapor is desorbed. The vapor flows through the vapor valve to the evaporator and condenses out there. At the end of the regeneration, the input of heat to the sorption agent is interrupted. The desorption of additional working agent vapor ends with this. The vapor valve is closed. The desorbed working agent is in liquid state in the working agent-storage material. The sorption agent is cooled afterwards to the ambient temperature by the release of heat through the outer wall of the sorption agent vessel.
To initiate the cooling phase, the vapor valve is opened. The working agent vapor can now flow from the evaporator into the sorption agent vessel and be exothermically sorbed by the sorption agent. The evaporating working agent is cooled in the evaporator and cools the vessel together with its contents. In order to produce the maximum cooling power, the sorption agent
Ammon Maximilian
Becky Andreas
Binnen Manfred
Inselkammer Jannik
Leibhard Martin
Bennett Henry
Hoffmann & Baron , LLP
Jones Melvin
Zeo-Tech (Zeolith-Technologie GmbH
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