Heat transfer device

Details Heat transfer device Heat transfer device

2000-01-27

2002-01-29

Doerrler, William (Department: 3744)

Refrigeration

Chemical reaction or solids dissolving

C062S380000, C062S060000

Reexamination Certificate

active

06341491

ABSTRACT:

This invention relates to heat transfer devices. In particular, but not exclusively, this invention relates to heat transfer devices for heating or cooling edible or drinkable materials.
The development of efficient and “environmentally-friendly” technologies for cooling drink and food products has been sought after. The trend towards more leisure time being spent in locations away from home is on the increase as the range and availability of outdoor entertainments and pastimes increases.
Advances have been made in developing cooling devices, including cold boxes, thermoelectric picnic coolers and portable chilling units. However, these units have the disadvantages of being bulky and expensive. One device, known as the “chill can” has been subjected to International restrictions owing to environmental concerns over its use. Furthermore, little attention has been paid to the development of heating devices for heating drinks and food products.
A lot of work has already been done in the area of self-cooling cans/self-heating cans (or other containers). In order to understand fully the remainder of this application the reader is now directed to read PCT/GB99/00255 (the contents of which are hereby incorporated into this application by reference), and to read: U.S. Pat. Nos. 4,978,495, 5,168,708, 736,599, WO 9 202 770, U.S. Pat. Nos. 4,771,607, 4,752,310, EP 0 726 433, U.S. Pat. Nos. 4,126,016, 5,088,302, 5,083,607, and 5,054,544, and our own earlier patent applications GB 2 329 461, GB 2 329 392, GB 2 329 459 and GB 2 333 586. Reading these documents, especially our own patent applications and PCT/GB99/00255, will assist in determining the full disclosure of the text and drawings that follow.
According to one aspect of the invention there is provided a heat transfer device containing a refrigerant, and said device further including operative means for allowing transfer of the refrigerant from a first region of the device to a second region of the device and means to drive said transfer of the refrigerant, thereby transferring heat from said first region to said second region, such that heat can be transferred to or from a material to be heated or cooled.
Preferably, the transfer of said refrigerant occurs by evaporation of the refrigerant. However, any other change of phase of a material may be used. For example sublimation of a solid to a gas may be used. The use of a phase change is advantageous because of the heat that must be absorbed to achieve this phase change.
Desirably, the means to drive said transfer of the refrigerant comprises a refrigerant take up agent to take up said refrigerant. Thus, heat can be extracted from the material by transfer of the refrigerant and heat is given out by the take up agent when the refrigerant is taken up thereby. The take up agent may be in the form of an adsorbent or absorbent.
According to another aspect of this invention there is provided a heat transfer device containing a refrigerant and a refrigerant take up agent, and said device further including operative means for allowing evaporation of the refrigerant whereby the take up agent takes up said evaporated refrigerant such that heat absorbed on evaporation of the refrigerant is evolved at the take up agent to enable heat to be transferred to or from a material to be heated or cooled.
Advantageuosly, the device is of a suitable size to be inserted in, or arranged in, or installed, or arranged around, a vessel suitable for holding a beverage or a foodstuff. Examples of such a vessel include beverage cans, bottles, cups, kegs, casks, and the like.
Preferably, the taking up of the refrigerant occurs at a first region of the device and evaporation of the refrigerant by the take up agent occurs at a second region.
The take up agent may be an adsorbent or an absorbent. Thus, heat of adsorption or absorption is given out when the evaporated refrigerant is adsorbed onto the adsorbent or absorbed by the absorbent and the heating or cooling of the material is enhanced.
Desirably, the device comprises a first part for the take up agent and a second part for the refrigerant. The first part is preferably at a lower pressure than the second part before the operative means is operated. An advantage of having the lower pressure in the first part is that evaporation of the refrigerant is enhanced once the pressures have been allowed to equalise.
In one embodiment, the second part may be at ambient pressure and the first part may be evacuated. In another embodiment, the second portion may be at above ambient pressure and the first part may be at ambient pressure. Alternatively, both the first and second parts are evacuated.
The skilled person will appreciate that the rate of evaporation is affected by the physical conditions surrounding the system in which evaporation is occurring. That is the pressure, temperature, temperature gradients, etc. will all affect the evaporation rate. Providing a low pressure environment may be advantageous because of a consequent reduction in the temperature at which evaporation of the refrigerant occurs.
In one embodiment the refrigerant may be water and the pressures in the first and second parts (once the operative means has allowed evaporation of the refrigerant) may be such that the water boils at substantially room temperature. Such a structure is clearly advantageous because boiling of the water will increase the rate of evaporation of the refrigerant which will speed the rate of cooling or heating of the material.
The first and second parts are advantageously isolated from each other, providing a structure in which the pressures can be maintained before activation of the operative means.
The operative means may be adapted to provide communication between the first and second parts on operation thereof. The first and second parts may be permanently attached to each other, for example they may be integral with each other. Alternatively, the first and second parts may be initially separate from each other to be attached together to allow communication therebetween on operation of the operative means.
The device may comprise a first element, which may be in the form of a first wall, on which the take up agent can be arranged, and a second element, which may be in the form of a second wall, to provide dispersion of the refrigerant.
The first element may be substantially cylindrical in shape, but it may be of any other suitable shape. The second element may be cylindrical in shape and dispersal means may be provided on said second element to disperse the refrigerant around the second element.
The dispersal means may comprise wicking means. The first and second elements are desirably spaced from each other to allow heat transfer from one to the other.
In one embodiment, the first part includes the second element and the second part may be in the form of a container adapted to release refrigerant into the second element on operation of the operative means.
In another embodiment, the second part may comprise the second element.
The operative means may comprise a release member adapted to provide an aperture in the second part to release said refrigerant or it may comprise an elongate rod having at one end thereof a substantially cylindrical member (the elongate rod and the cylindrical member may be thought of as a release means).
A membrane may be provided between the first and second parts to isolate the first part from the second part. The membrane may be formed of a metallic foil, for example aluminium foil. Alternatively, the membrane may be formed from a plastics material. Indeed, the membrane may be formed from any material which is compatible with the materials of the device.
A membrane compromising means (which may be the same as the release member) may be provided, adapted to pierce, rupture, cut or otherwise compromise said membrane so connecting said first and second parts. The operative means may comprise the membrane compromising means.
The skilled person will appreciate that the membrane compromising means should be adapted to allow communication between th

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