(1 ) Field of the Invention

This invention relates to refrigerated vehicles and containers.

(2) Prior Art

Conventional refrigeration units for refrig¬ erated vehicle bodies and shipping containers generally have a housing mounted externally on the front wall of the body or container. An opening in the front wall of the body or container enables a fan within the housing to draw air from the load space in the body or container into a plenum in the housing. The air is passed over the evaporator of the unit and then returned to the load space to refrigerate its contents. Examples of such conventional units are disclosed in AU-49252/79 (Thermo King Corporation) and US-4257240 (D.A. Christ¬ iansen et al - assigned to Thermo King Corporation).

The units provide little, if any, structural integrity to the bodies or containers on which they are mounted and the flow of air between the load space and the units is limited by the position and dimension of the opening in the front wall.

While the conventional units are fairly efficient for the storage and transport of frozen packed goods, they are not suitable for foods such as fresh fruits and vegetables which are preferably stored and transported at a high relative himidity e.g. 95%+. The conventional units dehumidify the air and moisture is lost from the foods, reducing their shelf life and their attractiveness to the customers.

SUMMARY OF THE PRESENT INVENTION It is an object of the present invention to provide a refrigeration or chiller unit for refrigerated vehicles or containers which maintains a high humidity

environment for products in the bodies or container ^' s.

It is a preferred object to provide a unit which can operate as a reverse cycle heating/cooling unit which can operate at high humidities in either mode.

It is a further preferred object to provide a unit which can also operate as a freezer at lower humidity.

It is a still further preferred object to provide a unit which is of modular construction to be mounted on the body or container as the front wall there¬ of and integral with the body or container.

It is a still further preferred object to provide a refrigerated vehicle body or container fitted with the refrigeration unit wherein baffles or guides in the load space direct the cooled air from the unit to form an "envelope" around the product in the load space. Other preferred objects of the present invent¬ ion will become apparent from the following description. In one aspect the present invention resides in a refrigeration unit for refrigerated vehicle bodies or containers including: a housing; a plenum in the housing to receive air to be cooled from the load space of the body or container; a fan or blower in the plenum; a refrigerator evaporator in the housing; a heat exchanger interposed between the evapor¬ ator and the plenum; water spray means adjacent the evaporator on the opposite side to the heat exchanger; and a cold air outler from the housing to direct the cold humidified air from the housing to the load space, so arranged that: water is sprayed over the evaporator and cooled,

the -cold water being received on the heat exchanger to form a large heat transfer surface area; the air from the plenum is passed over the heat exchanger to be cooled and humidified on contact with the cold water and then exhausted to the load space through the cold air outlet by the fan or blower.

Preferably the unit has a peripheral frame ^: around the housing to enable the housing to be mounted on the front of the body or container as the front wall thereof, the peripheral frame forming an integral part of the body or container.

Preferably the plenum, evaporator, heat exchanger, water spray means and cold air outlet are provided in a first compartment of the housing attached to the peripheral frame and adapted to be received within the body or container, the engines or motor, the compressor and the condensor of the refrigeration unit being provided in a second compartment of the housing on the front of the peripheral frame and enclosed by a aerodynamically shaped wall.

Preferably the water spray means include spray bars or a spray tree spaced about the coils of the evap¬ orator to direct the water onto the heat exchanger.

The heat exchanger may include a plurality of grids or meshes of fine wire provided in layers, or a plurality of layers of monofilament wires arranged alter¬ natively, the wires being adapted to .be coated with the cooled water sprayed over the evaporator- to provide a large heat transfer surface area between the cold water and the warm air.

The warm air may be directed through the heat exchanger in a counter-flow or cross-flow direction relative to the water flow.

' Preferably the water is collected- in a sump or tank at the bottom of the housing and recirculated to the

spray bars by a suitable pump. A moisture eliminator is preferably provided upstream of the cold air outlet to remove any water droplets from the cold air before it enters the load space. Preferably the plenum and cold-air outlet both extend across the full width of the lower portion and top portion, respectively, of the housing.

Preferably baffles or guides in the body or container, e.g. within the walls or attached thereto, direct the air flow from the cold air outlet to selected areas or zones of the body or container, the cold air preferably forming an "envelope" around the load space to prevent the ingress of external heat into the load space. The baffles or guides, or a false wall, may be provided to maintain the load at a minimum dis¬ tance from the walls to allow the cold air to pass between the load and the walls.

BRIEF DESCRIPTION OF THE DRAWINGS

To enable the invention to be fully under- stood, preferred embodiments will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a sectional side view of the refrigeration unit fitted as the front wall of a refrigerated vehicle body; FIG. 2 is a sectional plan view showing the mounting of the unit on the body;

FIG. 3 is an exploded view of three layers of the heat exchanger;

FIG. 4 is a sectional end view of one of the layers taken on line 4-4 on FIG. 3;

FIG. 5 is a schematic plan view of the air flow in the top of the vehicle body;

FIG. 6 is a schematic side view corresponding to FIG. 5; ^' FIG. 7 is a sectional end view showing the

air flow between the load and side wall; and

FIG. 8 is a sectional end view taken on line 8-8 on FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, the refrigerated vehicle body 10 is supported on a chassis with ground wheels and turntable (not shown).- The body has a floor 11, side walls 12, a roof 13 and hinged rear doors (not shown) . The front of the body 10 is open and receives the peripheral frame of the refrigeration unit 15 housed in a housing 16 which is curved along the top and at the front corners to reduce drag. The peripheral frame 1 is formed of C-section steel and is fixed to the walls etc. by a joining plate 17 so that the peri¬ pheral frame forms an integral part of the body 10.

The housing 16 is separated into a machinery compartment 18 and a cooling compartment 19, the latter being fitted within the body 10. A motor 20, mounted on a sub-frame 21, drives a compressor 22 for the refrigeration unit and a con- densor fan 23 draws air from outside the housing over the condensor 24 of the unit. An air flow shield (not shown) may be mounted on the prime-mover (also not shown) to direct air around the housing 16 to create a low pressure zone which draws air from the machinery compart¬ ment 18 via slots (not shown). This air flow over the condensor 24 assists in condensing the refrigerant and so enables the condensor fan 23 to cycle less frequently, thereby conserving power.

A plenum chamber 25 is provided across the lower portion of the cooling compartment 19 and is separated from the load space 26 of the body by a perforated or mesh wall 27. Warm air is drawn into the plenum chamber 25 from the load space 26, by a fan 27a driven by an

alternator (not shown) connected to the motor 20 and directed into the cooling compartment 19. Water is sprayed from a series of spray bars 28 onto the coils of the evaporator 29 at the top of the cooling compartment and the now cooled water forms a cold coating forming a high surface area thin film over a honeycomb or grid of fine wires forming a heat exchanger 30.

As shown in FIGS. 3 and 4, the heat exchanger 30 comprises a series of alternate layers 31 comprising monofilament metal wires-32 wound over peripheral wood or plastic frames 33- The alternating layers form a grid-like pattern in plan view. The counter-current flow of air (relative to the direction of the water spray) up through the heat exchanger 30 enables the warm air to transfer its heat to the water film on the monofilament wires 32 to cool and hunidify the air (e.g. to 100% R.H.). The now cool cold humid air passes through a moisture eliminator 34, which removes any droplets suspended in the air, and is directed into the load space 26 by a cold air outlet 35 which extends across the full width of the top of the cooling compart¬ ment 19.

The water from the heat exchanger 20 is collected in a sump 36 in the bottom of the cooling compartment and is pumped back to the spray bars 28 via an electric pump 37.

As the air entering the load space 26 is at high humidity e.g. 95-100% R.H., little, if any moisture loss from the product occurs.

When frozen products are being stored in the body 10, the water spray is not used and the unit 15 operates as a conventional freezer unit only at low humidity. To ensure greater protection-against the

ingress of eat, the cold air from the cold air outlet 35 is directed to form an "envelope" around the load space 26 by a series of baffles or guides 38. The load 39 is spaced from the walls and roof by the baffles 38 which may be e.g. U-shaped in section and fixed to the walls 12 and roof 13 of the body 10. As the air flow prevents the ingress of heat to the product, the walls may be manufactured from non-insulating material e.g. plastics - or fibreglass reinforced and/or coated marine plywood or other suitable timber. Preferably the walls are manufactured of insulating metal skin/expanded foam ¹ / metal skin insulating panels to further inhibit the ingress of external heat.

Referring to FIG. 5 the air from the cold air outlet 35 is directed into two side streams 40, 41 and a main stream 42.

Referring to FIGS. 5 and 6, the side stream 41 cools approximately one-quarter of the roof area and is then directed downwardly and forwardly in the top left-hand half of the side wall 12 as indicated in dashe lines, back towards' the plenum chamber 25. The side stream 40 cools the corresponding portion of roof and side wall on the other side of the body.

The main stream 42 fans out to cool the majority of the roof area 14 and a portion is then directed down the rear doors and back along the floor 11 under the load. A portion o_f the ma ^' in stream 42 is directed to cool the remainder of each side wall, being directed forwardly and downwardly by the baffles 38. A further portion of the air flow of the main stream 37 is directed from the ceiling to cool the load space. In this manner the load space 26 is fully enveloped by cold air, with some cold air passing through the load space. The particular arrangement of the baffles 38 may be varied to suit the particular

intended applications to ensure the continuous air flow around the load space. When the walls and roof are formed of spaced plywood panels, the baffles 38 can be provided between the panels to direct the cold air between the panels, slots being provided in the inner panel to direct the cool air into the load space 26.

It will be readily apparent to the skilled addressee that various changes and modifications may be made to the embodiment described without departing from the scope of the present invention defined in the appended claims.