NZ210747A - Refrigeration unit:circulating air passed through water spray - Google Patents

Description

Priority D»v.e(s}: .... f?if?.-.... Complete Specification fifed: •ft. ?.57 £5 DtC''?C5'" Publication Date: P.O. Journal, No: ....

Patents Form No. 5 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION "REFRIGERATED VEHICLES AND CONTAINERS." /St, WE FURLEY PTY. LTD. , a Company incorporated in the State of Queensland, of 71 Gustavson Street, Annerley, Queensland 4103, Australia, ,»r\ hereby declare the invention, for which jt-/we pray that a patent may be granted to ipe/us, and the method by which it is to be performed, to be particularly described in and by the following statement 1. (followed by pogc. ii\.) 210747 _JV£_PAmv-,;Fr;CE " 4 JAN1985 "'iCEivr 2 10747 -1 A~- Ti tie : "REFRIGERATED VEHICLES AND CONTAINERS" BACKGROUND OF THE INVENTION (1) Field of the Invention This invention relates to refrigerated vehicles and containers. (2) Prior Art Conventional refrigeration units for refrigerated 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 jbf such conventional units are disclosed in AU-1l9252/79 (Thermo King Corporation) and US-'I2572'I0 (D.A. Christiansen 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 Sheet 2 of 15 21074? environment for products in the bodies or containers.

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 oan 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 thereof 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 invention 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 refrigeration evaporator having a plurality of coils in the housing; a heat exchanger interposed between the evaporator and the plenum, the heat exchanger comprising a plurality of layers of grids, mesh or monofilament wires; water spray means adjacent the evaporator i:.;: " . , ■ - v 210747 n •3- on the opposite side to the heat exchanger; the water spray means including spray bars on a spray tree spaced above the coils of the evaporator to direct water onto the heat exchanger; 5 a cold air outlet 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 10 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 "w' through the cold air outlet by the fan or blower; and wherein the plenum, fan or blower, evaporator, heat exchanger, water spray means and cold air outlet are provided in a first compartment of the housing, the first compartment being mountable within the body or container; an engine or motor, compressor and condensor for the refrigeration unit are provided in a separate second compartment in the housing; "the unit being so arranged to form an end wall of the body or container".

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 *0 thereof, the peripheral frame forming an integral part of the body or container.

The warm air may be directed through the heat exchanger in a counter-flow or cross-flow direction relative to the water flow. s—•' Preferably the water is collected in a sump or tank at the bottom of the housing and recirculated to 35 the /v \245epl98{§ /■ «.V O — f 2 10747 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, 10 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, 15 may be provided to maintain the load at a minimum distance 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-20 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 30 layers taken on line 'l-'l 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 Sheet 5 of 15 2 10747 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 11 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 2'J 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 Sheet 6 of 15 ^mstmsss •» "0747 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 5 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 G 30- As shown in FIGS. 3 and 'I, the heat exchanger 10 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 >wr 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 3'l, which removes any 20 droplets suspended iri 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 compartment 19.

The water from the heat exchanger 20 is 25 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 30 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 Sheet 7 of 15 210747 ingress of heat, 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 nori-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 foam7 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 ')0, '11 and a main stream '12.

Referring to FIGS. 5 and 6, the side stream 11 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 dashed 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 '12 fans out to cool the majority of the roof area 1'I and a portion is then directed down the rear doors and back along the floor 11 under the load. A portion of the main stream 'J2 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 Sheet 8 of 15 G n G 2 1074 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 5 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 10 be made to the embodiment described without departing from the scope of the present invention defined in the appended claims.

Sheet 9 of 15

Claims (9)

1. 210747 -9- WI1AT WE CLAIM IS: 1 . 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 refrigeration evaporator having a plurality of coils in the housing; a heat exchanger interposed between the evaporator and the plenum; the heat exchanger comprising a plurality of layers of grids, mesh or monofilament wires; water spray means adjacent the evaporator on the opposite side to the heat exchanger; the water spray means including spray bars on a spray tree spaced above the coils of the evaporator to direct water onto the heat exchanger; the cold humidified air from the housing to the load space; so arranged that: cooled, the cold water being received on the heat exchanger to form a large heat transfer surface area; 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; and tor, heat exchanger, water spray means and cold air outlet are provided in a first compartment of the housing, the first compartment being mountable within the body or container ; an engine or motor, compressor and condensor for the refrigeration unit are provided in a a cold air outlet from the housing to direct water is sprayed over the evaporator and the air from the plenum is passed over the wherein the plenum, fan or blower, evapora- -10- 210747 separate second compartment in the housing; the unit being so arranged to form an end wall of the body or container .
2. 2. A unit as claimed in Claim 1 wherein: the warm air from the plenum is directed through the heat exchanger in a counter-flow or cross-flow direction relative to the water flow to enable effective heat transfer from the warm air to the cold water.
3. 3- A unit as claimed in Claim 2 wherein: the water is collected in a sump or tank in the bottom of the housing and is recirculated to the spray means ; and a moisture eliminator is provided upstream of the cold air outlet to remove water droplets from the cold air before it enters the load space.
4. 4. A. refrigeration unit as claimed in any one of Claims 1 to 3 wherein: a peripheral frame is provided around the housing, with the peripheral frame being integral with the body or container.
5. 5. A refrigerated vehicle body or container including: a floor; a pair of side walls; a roof; and one end wall, wherein: the refrigeration unit as claimed in any one of Claims 1 to 4 is provided at the other end of the body or container, the housing forming the other end wall.
6. 6. A body or container as claimed in Claim 5 wherein : the plenum and cold air outlet extend across the full width of the body or container; and baffles or guides in the body or container direct the cold air from the cold air outlet to the plenum to form an envelope of cold air around any load in the load 210747 -11- space of the body or container,
7. 7. A body or container as claimed in Claim 6 wherein: the baffles or guides maintain the load at a distance from the floor, roof and walls of the body or container to allow th«j cold air to pass around the load in the load space.
8. 8. A refrigeration unit for refrigerated vehicle bodies or containers .-substantially as hereinbefore described with reference to FIG.*;. 1, 3 and 4 of the drawings.
9. 9. A refrigerated vehicle body or container substantially as hereinbefore described with reference to FIGS. 1 to 4, or FIGS. 1 to 8, of the accompanying drawings.