A portable chilling unit

Abstract: A portable chilling unit (10) for chilling either the whole or a selected portion of the interior of a container (22) comprises a plurality of eutectic elements (26) adapted for pre-chilling by exposure to liquid cryogen, a height adjustable inlet (16) and an outlet towards the base of the unit (10). An insulating blanket (56) is attachable to the inlet such that, in operation, the blanket (56) may be placed over the cargo to be chilled and only atmosphere from under the blanket is drawn through the unit for chilling.

Description: The present invention relates to a portable chilling unit as defined in the preamble of claim 1. Such a unit is known, for example, from DE-C-38 07 879. The invention relates more particularly, but not exclusively, to such units for use in refrigerating the interior of cargo containers so as to maintain chilled food-stuffs and/or other materials disposed therein below a predetermined temperature. Presently known mechanical chilling devices are usually fixed to and pass through the front bulkhead of containers, road vehicles or railway wagon bodies. The chilling devices are driven either by an internal combustion engine forming part of the device or by an electric motor supplied with current generated by, in the case of road vehicles that vehicle's engine or in the case of railway by an axle mounted generator. With containers, road vehicles and wagons employing eutectic beams or plates for cooling purposes the plates or beams are usually mounted on the inside of the walls or roof. Eutectic beams are frozen to operational temperatures by either an externally mounted refrigeration compressor, driven by an internal combustion engine, or by an external source of electric power which is deconnected when freezing is complete and the container or vehicle is about to enter service. In either instance the vehicle mounted equipment occupies valuable cargo space especially when the container or vehicle is to be used for the carriage of goods not requiring a controlled atmosphere. In addition such equipment tends to cool the entire atmosphere within the cargo compartment rather than just that surrounding the produce therein. DE-C-3807879, for example, discloses a device for cooling the interior of a motor vehicle in which a fan blows air through a cold storage battery containing a eutectic solution and which can be chilled in, for example, a domestic refrigerator. It is an object of the present invention to provide a portable chilling unit which reduces and possibly eliminates the problems associated with the above mentioned devices. Accordingly, the present invention comprises a portable chilling unit positionable within a container and for chilling the interior or part thereof, said unit comprising a thermally insulated compartment having a chilling means positioned therein and having an inlet for receiving atmosphere from the interior of the container, drawing means for drawing atmosphere into the compartment and expelling said atmosphere from the compartment through an outlet positioned below said inlet, said chilling means comprising a plurality of eutectic elements adapted for pre-chilling by exposure to the chilling effect of liquid cryogen, characterised by an insulating blanket for placement over any cargo positioned within said container, said inlet being positioned immediately under said blanket for drawing atmosphere from thereunder. Advantageously, the unit includes a sensor for sensing the temperature of the atmosphere surrounding any cargo in said container. The unit may further include a fan for drawing a sample of atmosphere and for directing it to said sensor. Advantageously, the fan is periodically operable. Preferably, the unit includes securing means for securing an edge of the blanket to the inlet. Preferably, the inlet is height adjustable. In a particularly convenient arrangement the outlet comprises a base portion of said insulated compartment and is positioned for directing chilled atmosphere into the void space between portions of a standard pallet upon which said unit is positionable. Advantageously, said eutectic elements extend along a longitudinal axis X and the unit further comprises an intake plenum chamber for receiving atmosphere from the inlet and having a plurality of outlet slots extending in a direction substantially parallel with the longitudinal axis of said eutectic elements and for orientating the flow of incoming atmosphere so as to promote the smooth flow of atmosphere over and around said eutectic elements. In a particularly efficient arrangement the unit further includes an outlet plenum chamber having a plurality of slotted inlets shaped and positioned for directing atmosphere received from a region containing said eutectic elements and for orientating the flow of said atmosphere into said outlet plenum in a manner which promotes smooth flow therethrough, said outlet plenum further including said outlet positioned at the bottom thereof. The present invention will now be more particularly described by way of example only with reference to the accompanying drawings in which: Figure 1 is an isometric, part exposed, view of a chilling unit according to the present invention; Figure 2 is a general view of the unit shown in Figure 1 when arranged in relationship within an insulating blanket forming part of the present invention and a cargo to be chilled; and Figure 3 is a cross sectional view of a sensor arrangement forming part of the present invention and Figure 4 is an enlarged view of the inlet portion of the unit. Referring to Figure 1, the chilling unit 10 comprises a compartment 12 having all outer wall 14 insulated by insulating material 14a. An inlet 16 is provided in an insulated Tambour shutter 18 in a manner which allows the inlet to be moved vertically so as to alter its position to match that required. A fan 20 (not shown) provides a means for drawing air or whatever atmosphere is contained within the container 22 into the chilling unit as and when required and for causing the chilled atmosphere to flow through the unit and out of an outlet 24. A plurality of eutectic elements 26 each of which extend along a longitudinal axis x are provided in a central region 28 and further insulated from the inlet 16 and outlet 24 by inner walls 27, 29 each formed from material having a relatively high value of thermal insulation. Preferably, each eutectic element 26 comprises an outer tube 30 having a co-axial inner tube 32 passing therethrough and a mass of eutectic material 34 such as magnesium chloride filling the space there between. The inner tubes 32 are each connected to a supply coupling 36 through which liquid cryogen is passed during a chilling step to be described in detail later herein. The eutectic elements 26 may be connected to each other, either in series or in parallel or in groups arranged in either series or in parallel, whichever best suits the particular arrangement. An inlet plenum chamber 38 is formed between the wall having inlet 16 positioned therein and inner wall 27 which is provided with a plurality of slotted outlets 40 linking the plenum chamber 38 with the region containing the eutectic chilling elements 26. The slotted outlets 40 are each arranged to extend in a direction substantially parallel to the longitudinal axis x of the eutectic elements 26 so as to direct incoming atmosphere into central region 28 in a manner which promotes the smooth flow of said atmosphere over and around the eutectic elements 26. An outlet plenum chamber 42 is formed between inner wall 29 and a second outer wall 14. A plurality of slotted inlets 44 provided in inner wall 29 are shaped and positioned for directing atmosphere received from region 28 and for orientating the flow of said atmosphere into said outlet plenum in a manner which promotes smooth flow therethrough. Any atmosphere passing through the outlet plenum is directed downwardly towards outlet 24 positioned adjacent to or within the base 46 of said unit 10. Preferably, the outlet 46 is positioned for directing atmosphere into the void space between portions of a pallet 48 upon which said unit 10 is positionable. Alternatively, the outlet may be positioned for directing chilled air in any one of a number of preferred directions. Atmosphere exiting the unit 10 is free to pass through the open spaces in the pallet and flow towards the base of the cargo positioned with the container 22 in a manner to be described in detail later herein. The inlet 16 is provided with a securing means 50 in the form of, for example, a rubber keeper 52 and spikes 54 between which an edge of an insulating blanket 56 may be secured so as to ensure atmosphere is drawn from immediately thereunder. The insulating blanket 56, advantageously made from some form of closed cellular material such as that known as "bubble pack" and having a reflective surface provided thereon, is draped over any cargo in the container so as to provide an insulating cover. The atmosphere underneath the blanket being controlled by the chilling unit 10. A sampling device or "sniffer" 60 is employed to sample continuously the atmosphere to be temperature controlled and to initiate operation of a main fan 20 as and when required. The "sniffer" 60 comprises a small, low power, electric fan 62 and a temperature sensor 64 positioned in the flow of any sampled atmosphere. The "sniffer" 60 further includes control means (not shown) for initiating operation of main fan 20 as and when required. Preferably, the "sniffer" 60 is positioned adjacent to the intake 16 so as to sample the warmest atmosphere under the blanket 56. A battery 66 is provided for powering fans 20 and 62. In operation, the eutectic elements 26 are pre-chilled by allowing a quantity of cryogenic fluid, such as liquid nitrogen, to flow through inner tubes 32 so as to allow some of the chill contained therein to pass to the eutectic material 34. Once the eutectic material 34 is sufficiently chilled, surplus nitrogen is vented to atmosphere so that no liquid nitrogen remains in the tubes during subsequent operation of the unit. The highly insulated walls 14 effectively act to ensure that the eutectic elements 26 remain as cold as possible for as long as possible and ensure that their chilling effect is only utilised as and when required. After the unit 10 has been chilled, it may be placed in the container adjacent to the cargo to be subjected to temperature control. The insulating blanket 56 once draped over the selected cargo and secured to the inlet 16 effectively acts to define the boundary of the atmosphere to be chilled. Whenever the sensor (described later herein) detects that the temperature of the atmosphere under the blanket has risen above a predetermined value it acts to initiate control over the main fan 20 so as to draw atmosphere from the upper regions of the cargo and into plenum chamber 38 where it is orientated for flowing over the eutectic elements 26. Each eutectic element will act to chill the atmosphere passing thereover such that the atmosphere exiting unit 10 via outlet 24 will tend to be much cooler than that being drawn thereinto. The chilled atmosphere is directed back towards the cargo and tends to rise through the cargo as it surrenders its chilling capacity thereto. Clearly, if the cargo is all placed on pallets such as that upon which the unit 10 is positioned, then chilled atmosphere will be free to flow between the gaps in said pallets and act on the underside of the cargo as well as its sides. It will be appreciated that one could use a number of the above units in one cargo container either to increase the cooling capacity or to create zones of differing temperatures, each protected by its own insulating blanket and each being suitable for a particular cargo. It will also be appreciated that by limiting the volume of atmosphere to be chilled to that under the insulating blankets one will not be chilling the entire atmosphere within the container and hence it will be possible to increase significantly the effective operational life of such units. Additionally, the use of a temperature sensor and sampling device ensures that the unit is only used when chilling is actually required, thereby avoiding the possibility of over chilling the cargo.

Claims: A portable chilling unit (10) positionable within a container (22) and for chilling the interior or part thereof, said unit comprising a thermally insulated compartment (12) having a chilling means (26) positioned therein and having an inlet (16) for receiving atmosphere from the interior of the container (22), drawing means (20) for drawing atmosphere into the compartment (12) and expelling said atmosphere from the compartment (12) through an outlet (24) positioned below said inlet (16), said chilling means (26) comprising a plurality of eutectic elements (26) adapted for pre-chilling by exposure to the chilling effect of liquid cryogen, characterised by an insulating blanket (56) for placement over any cargo positioned within said container (22), said inlet (16) being positioned immediately under said blanket (56) for drawing atmosphere from thereunder. A chilling unit as claimed in Claim 1 characterised by a sensor (64) for sensing the temperature of the atmosphere surrounding any cargo in said container. A chilling unit as claimed in Claim 2 characterised by a fan (62) for drawing a sample of atmosphere and for directing it to said sensor (64). A chilling unit as claimed in Claim 3 in which said fan (62) is continuously operable. A chilling unit as claimed in any one of Claims 1 to 4 characterised by securing means (52, 54) for securing an edge of said blanket to said inlet (16). A chilling unit (10) as claimed in any one of Claims 1 to 5 characterised in that said inlet (16) is height adjustable. A chilling unit (10) as claimed in any one of the preceding claims characterised in that the outlet (24) comprises a base portion (46) of said insulated compartment (12) and is positioned for directing chilled atmosphere into the void space between portions of a pallet (48) upon which said unit (10) is positionable. A chilling unit (10) as claimed in any one of the preceding claims characterised in that said eutectic elements (26) extend along a longitudinal axis X and the unit (10) further comprises an intake plenum chamber (38) for receiving atmosphere from the inlet (16) and having a plurality of outlet slots (40) extending in a direction substantially parallel to the longitudinal axis of said eutectic elements (26) and for orientating the flow of incoming atmosphere so as to promote the smooth flow of atmosphere over and around said eutectic elements (26). A chilling unit (10) as claimed in any one of the preceding claims characterised by an outlet plenum (42) chamber having a plurality of slotted inlets (44) shaped and positioned for directing atmosphere received from a region containing said eutectic elements (26) and for orientating the flow of said atmosphere into said outlet plenum (42) in a manner which promotes smooth flow therethrough, said outlet plenum (42) further including said outlet (24) positioned at the bottom thereof.

Inventors: GOODALL PETER FRANK, GOODALL, PETER FRANK
Applicants: BOC GROUP PLC, THE BOC GROUP PLC
Application year: 1995
Main classification: F25D3
IPC codes: F25D3, F25D11