GB1594576A - Refrigeration apparatus - Google Patents

Description

(54) REFRIGERATION APPARATUS (71) We, BOC LIMITED, of Hammersmith House, London W6 9DX, England, an English company, do hereby declare the invention, for which we pray that a patent may he granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- -This invention relates to refrigerationapparatus particularly, but not exclusively, for use in containers for perishable goods so as to freeze or cool the goods to a temperature below ambient and maintain them there.

Liquid nitrogen has been used extensively in the food industry for cooling or freezing foodstuffs in refrigerated containers, cabinets or other compartments. Generally liquid nitrogen is passed through a number of spray nozzles which direct nitrogen gas evaporated from the liquid nitrogen onto foodstuffs located in the compartment. Disadvantages of known systems, are first, that the liquid nitrogen throughput is limited because of poor heat exchange between liquid nitrogen issuing from the nozzle orifices and the surrounding atmosphere and, secondly, that the heat transfer between the liquid nitrogen, or nitrogen gas evaporated therefrom, and the product to be cooled or frozen is poor on account of the relatively slow gas movement in the compartment.

According to the present invention there is provided refrigeration apparatus for location in an enclosed compartment to provide circulation of cooled gas therein,.

comprising a duct enclosing an impeller adapted to draw in a gaseous medium through one end of the duct and deliver the same through the other end of the duct, a plurality of spray devices in the duct downstream of the impeller, and means for supplying a cryogenic liquid to said spray devices so as to spray such liquid into such stream to cool the stream by evaporation of the liquid.

Preferably, the spray devices (e.g.

nozzles) are arranged along an endless path, e.g. an annular path, at least some of the nozzles or spray devices being arranged so as to direct sprays of the cryogenic medium towards the impeller. The impeller may be adapted to direct said flow of gas or gaseous mixture to pass through the space surrounded by said path. At least some of the nozzles or spray devices may be arranged so as to direct sprays of cryogenic medium perpendicular to the axis of the duct. It is also preferred that the nozzles or spray devices are joined by at least one manifold for cryogenic liquid extending along said path.

In use a refrigeration apparatus according to the invention is located in a freezer cabinet or room and the air or air/nitrogen mixture is passed through the apparatus to provide a blast of cooled air or gas mixture which circulates within the cabinet or room. Some of the gas will be passed several times through the unit thereby receiving a fresh boost of refrigeration each time.

One embodiment of a refrigeration apparatus according to the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a front elevation of a refrigeration apparatus embodying the invention, and, Figure 2 is a perspective view of the refrigeration apparatus of Figure 1.

Referring to the drawings, there is a refrigeration apparatus 10 for location in an insulated food storage cabinet or room. The unit comprises a tubular housing 11 in which a nine bladed fan or impeller 12 is mounted. The fan size is 24 inches (i.e. its diameter is 24 inches) and its power output is 2 HP. The fan creates gas flow rates which can be varied up to 10,000 cubic feet per minute. A series of twelve equally spaced fixed guide vanes 13 are mounted around the inner periphery of the forward end of the housing 11.

A liquid nitrogen spray header 14 is -mounted in the housing 11 at its forward end. The header 14 comprises an annular manifold 15 provided with twenty two equiangularly spaced spray nozzles 16 directed inwardly of the annulus defined by the manifold (i.e. towards the impeller or fan 12). A pipeline 17, connected to a vacuum insulated vessel (not shown) containing liquid nitrogen, supplies the manifold 15. In other embodiments, it is possible for half of the nozzles 16 to be directed axially of the annular manifold 15 in the direction away from the fan 12, but in practice it is preferred to adopt the arrangement shown in the drawings.

The fan creates a high velocity flow of air or air/nitrogen mixture from the cabinet or room in which the unit 10 is located through the ring of nozzles 16 thereby enabling relatively large quantities of liquid nitrogen to be evaporated, for example 0.75 tons/hour. In this way air or air/nitrogen spray is continuously circulated at relatively high velocity throughout the cabinet or room thereby assisting heat exchange with the products to be cooled or frozen.

An adjustable control device, in the form of three pivotally mounted butterfly valves 18, is located at the rear end of the housing to control the velocity of the air flow. In other embodiments such control may be effected by the provision of a thryistor placed in series with the fan motor windings. In many practical applications of an evaporator as described above, it is expected that no such air flow control device will be required.

One example of freezer in which the above described unit 10 can be used is a spiral freezer. Products to be cooled or frozen pass through the freezer on a conveyor which moves along a helical path.

One or more - evaporator units 10 are located in the freezer to provide high velocity flows of cold air which pass over the products to cool them in an efficient manner. Another possible use of the above described evaporation unit 10 is in an apparatus as described in UK patent No.

1531461 in place of the liquid nitrogen spray jets of that apparatus.

WHAT WE CLAIM IS: 1. Refrigeration apparatus for location in an enclosed compartment to provide circulation of cooled gas therein, comprising a duct enclosing an impeller adapted to draw in a gaseous medium through one end of the duct and deliver the same through the other end of the duct, a plurality of spray devices in the duct downstream of the impeller, and means for supplying a cryogenic liquid to said spray devices so as to spray such liquid into such stream to cool the stream by evaporation of the liquid.

2. Apparatus as claimed in claim 1, in which the nozzles are arranged along an endless path.

3. Apparatus as claimed in claim 2, in which the endless path is annular.

4. Apparatus as claimed in any one of the preceding claims, in which the nozzles are arranged so as to spray the cryogenic liquid towards the impeller.

5. Refrigeration apparatus for location in an enclosed compartment to provide circulation of cooled gas therein, substantially as described herein with reference to, and as shown in, the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   end. The header 14 comprises an annular manifold 15 provided with twenty two equiangularly spaced spray nozzles 16 directed inwardly of the annulus defined by the manifold (i.e. towards the impeller or fan 12). A pipeline 17, connected to a vacuum insulated vessel (not shown) containing liquid nitrogen, supplies the manifold 15. In other embodiments, it is possible for half of the nozzles 16 to be directed axially of the annular manifold 15 in the direction away from the fan 12, but in practice it is preferred to adopt the arrangement shown in the drawings.

   The fan creates a high velocity flow of air or air/nitrogen mixture from the cabinet or room in which the unit 10 is located through the ring of nozzles 16 thereby enabling relatively large quantities of liquid nitrogen to be evaporated, for example 0.75 tons/hour. In this way air or air/nitrogen spray is continuously circulated at relatively high velocity throughout the cabinet or room thereby assisting heat exchange with the products to be cooled or frozen.

   An adjustable control device, in the form of three pivotally mounted butterfly valves 18, is located at the rear end of the housing to control the velocity of the air flow. In other embodiments such control may be effected by the provision of a thryistor placed in series with the fan motor windings. In many practical applications of an evaporator as described above, it is expected that no such air flow control device will be required.

   One example of freezer in which the above described unit 10 can be used is a spiral freezer. Products to be cooled or frozen pass through the freezer on a conveyor which moves along a helical path.

   One or more - evaporator units 10 are located in the freezer to provide high velocity flows of cold air which pass over the products to cool them in an efficient manner. Another possible use of the above described evaporation unit 10 is in an apparatus as described in UK patent No.

   1531461 in place of the liquid nitrogen spray jets of that apparatus.

   WHAT WE CLAIM IS: 1. Refrigeration apparatus for location in an enclosed compartment to provide circulation of cooled gas therein, comprising a duct enclosing an impeller adapted to draw in a gaseous medium through one end of the duct and deliver the same through the other end of the duct, a plurality of spray devices in the duct downstream of the impeller, and means for supplying a cryogenic liquid to said spray devices so as to spray such liquid into such stream to cool the stream by evaporation of the liquid.
2. 2. Apparatus as claimed in claim 1, in which the nozzles are arranged along an endless path.
3. 3. Apparatus as claimed in claim 2, in which the endless path is annular.
4. 4. Apparatus as claimed in any one of the preceding claims, in which the nozzles are arranged so as to spray the cryogenic liquid towards the impeller.
5. 5. Refrigeration apparatus for location in an enclosed compartment to provide circulation of cooled gas therein, substantially as described herein with reference to, and as shown in, the accompanying drawings.