Patent Description:
A typical refrigerated cargo container, such as those utilized to transport cargo via sea, rail or road, is a container modified to include a refrigeration unit located at one end of the container. The refrigeration unit includes a compressor, condenser, expansion valve and evaporator. A volume of refrigerant circulates throughout the refrigeration unit, and one or more evaporator fans of the refrigeration unit blow a flow of supply air across the evaporator thereby cooling the supply air and forcing it out into the container.

An atmosphere control system controls the amount of oxygen and carbon dioxide inside the refrigerated container to, for example, change the rate of ripening of produce stored in the container. The atmosphere control system may control the amount of oxygen (O2) and carbon dioxide (CO2) in the container. <CIT> discloses a container refrigeration apparatus comprising an air compressor configured to generate compressed air, the air compressor located outside the container, and a first and second separator configured to receive the compressed air and output nitrogen into the interior of the container. A valve between the compressor and the first and second separators controls which of the separators the compressed air is directed to. <CIT> discloses a storage cabinet comprising a pressure increasing means connected upstream of an oxygen removal device. Outside air is received by the pressure increasing means and oxygen depleted gas from the oxygen removal device is received by a storage compartment of the storage cabinet. <CIT> discloses an indoor air-conditioning device which includes a gas supply device and a controller which together perform a gas supply operation of supplying nitrogen-enriched air into a container such that the inside air has a desired composition.

An aspect of the invention provides a refrigeration unit as claimed in claim <NUM>.

The valve, in a closed position, may direct compressed air to the separator.

The refrigeration unit may include a controller configured to control the valve to move between the open position and the closed position.

The controller may be configured to control the compressor.

The refrigeration unit may include a sensor in the evaporator section, the sensor may be configured to measure a level of a gas in the container; wherein the controller may be configured to move the valve between the open position and the closed position in response to the level of the gas in the container.

The atmosphere control system may comprise at least one filter between the water separator and the separator.

The at least one filter may be located in the condenser section, or the at least one filter may be located in the evaporator section.

Technical effects of embodiments of the present disclosure include the provision of an air compressor of an atmosphere control system in a condenser section of a refrigeration unit for use with a container.

Shown in <FIG> is a refrigerated container <NUM>. The container <NUM> has a generally rectangular construction, with a top wall <NUM>, a directly opposed bottom wall <NUM>, opposed side walls <NUM> and a front wall <NUM>. The container <NUM> further includes a door or doors (not shown) at a rear wall <NUM>, opposite the front wall <NUM>. The container <NUM> is configured to maintain a cargo <NUM> located inside the container <NUM> at a selected temperature through the use of a refrigeration unit <NUM> located at the container <NUM>. The container <NUM> is mobile and is utilized to transport the cargo <NUM> via, for example, a truck, a train or a ship. The container <NUM> may be integrated with a trailer or chassis. The refrigeration unit <NUM> is located at the front wall <NUM>, and includes a compressor <NUM>, a condenser <NUM>, an expansion device <NUM> (e.g., a TXV or EXV), an evaporator <NUM> and an evaporator fan <NUM> (shown in <FIG>), as well as other ancillary components.

Referring to <FIG>, the refrigeration unit <NUM> flows return air <NUM> across the evaporator <NUM> via the evaporator fan <NUM>, thus cooling the return air <NUM> to a selected temperature and urges the cooled return airflow <NUM>, now referred to as supply air <NUM>, through a refrigeration unit outlet <NUM> into the container <NUM> via, for example, openings <NUM> in one or more T-bars <NUM> extending along the bottom wall <NUM> of the container <NUM> to cool the cargo <NUM>.

The refrigeration unit <NUM> is separated into an evaporator section <NUM> containing the evaporator <NUM>, the evaporator fan <NUM> and an evaporator fan motor <NUM> and a condenser section <NUM> containing the compressor <NUM>, the condenser <NUM> and the expansion device <NUM>. The expansion device <NUM> may be located in the evaporator section <NUM>. The evaporator section <NUM>, which may be located above the condenser section <NUM>, is separated from the condenser section <NUM> by a panel <NUM> that extends across the refrigeration unit <NUM>. The condenser section <NUM> is exposed to ambient air and may be covered by panels having openings formed therein. In operation, refrigerant is circulated in serial fashion through the compressor <NUM>, the condenser <NUM>, the expansion device <NUM>, the evaporator <NUM> and back to the compressor <NUM>. It is understood that the refrigeration unit <NUM> may include additional components (e.g., economizer, receiver, SMV, etc.) that are not shown.

Referring now to <FIG>, the refrigeration unit <NUM> includes a housing <NUM> to contain components of the refrigeration unit <NUM>. Optionally, the housing <NUM> is separate and distinct from the container <NUM>, or alternatively, the housing <NUM> is an integral part of the container <NUM>. A condenser fan <NUM> is driven by a condenser motor (not shown) to drive air over the condenser <NUM> and discharge the air outside the refrigeration unit <NUM>. The condenser <NUM> may be radially disposed about the condenser fan <NUM>. A controller <NUM> controls operation of the refrigeration unit <NUM>, for example, by controlling the compressor <NUM> (e.g., on/off/variable speed), evaporator fan motor <NUM> (e.g., on/off/variable speed), condenser fan motor (e.g., on/off/variable speed), etc. The controller <NUM> may be implemented user a processor-based device including a microprocessor, memory, user interface, I/O inputs, etc. The controller <NUM> controls components of the refrigeration unit <NUM> to maintain a desired temperature within the interior of the container <NUM>, as known in the art. An air compressor <NUM> is located in the condenser section <NUM>. The air compressor <NUM> is a component of an atmosphere control system <NUM> (<FIG>) that operates to regulate atmosphere (e.g., oxygen and carbon dioxide) in the interior of the container <NUM>.

<FIG> depicts the atmosphere control system <NUM> in an example embodiment. The atmosphere control system <NUM> operates to control levels of at least one gas inside the container <NUM>. In an embodiment, the atmosphere control system <NUM> operates to control levels of oxygen and/or carbon dioxide. The atmosphere control system <NUM> includes the air compressor <NUM> located in the condenser section <NUM> and thus outside the interior of the container <NUM>. The controller <NUM> may turn on the air compressor <NUM> by sending a signal to a relay or contactor that applies power to the air compressor <NUM>. When turned on, the air compressor <NUM> draws air from outside the container <NUM> through a first filter <NUM> (e.g., a <NUM> micron particulate filter). The compressed air produced by the air compressor <NUM> flows from the condenser section <NUM> into the evaporator section <NUM> to a heat exchanger <NUM>. The heat exchanger may be an air-cooled heat exchanger of various types (e.g., round tube plate fin, microchannel, etc.). At heat exchanger <NUM>, the compressed air is cooled to facilitate water removal. From the heat exchanger <NUM>, the compressed air flows to a water separator <NUM> where water is removed. From the water separator <NUM>, the compressed air flows to a second filter <NUM> (e.g., a <NUM> micron particulate filter) and a third filter <NUM> (e.g., a <NUM> micron particulate filter). The second filter <NUM> and the third filter <NUM> may be located in the condenser section or the evaporator section <NUM>.

From the second filter <NUM> and the third filter <NUM>, the compressed air flows to a first valve, V1. The first valve V1 has two outlets, which can be controlled by controller <NUM>. When the first valve V1 is in a first position (e.g., an open position when energized), the compressed air is output from the first valve V1 to the interior of the container <NUM>. The first valve V1 may be located to provide the air upstream of the evaporator <NUM>. When the first valve V1 is in a second position (e.g., a closed position when not energized), the compressed air is directed to a separator <NUM>. The separator <NUM> may be a membrane separator that generates an output of highly pure, separated nitrogen upstream of evaporator <NUM>. Other atmospheric gases, including oxygen, argon and carbon dioxide, are vented to the condenser section <NUM> and outside of the refrigeration unit <NUM>. The nitrogen from separator <NUM> is directed to a second valve V2. The second valve V2 is a bleeder port that allows a small portion of the nitrogen from the separator <NUM> to be sent to a nitrogen sensor <NUM> to measure the purity of the nitrogen. The second valve V2 may be controlled by the controller <NUM>.

When nitrogen is provided upstream of the evaporator <NUM>, the nitrogen enters the interior of the container <NUM> and forces oxygen and carbon dioxide out of the interior of the container <NUM>. Reducing the oxygen level in the container <NUM> reduces ripening of produce. Reducing the carbon dioxide level in the container <NUM> prevents damage to cargo in the container due to high carbon dioxide levels.

In operation, the controller <NUM> monitors levels of at least one gas inside the container <NUM>, using oxygen sensor <NUM> and/or carbon dioxide sensor <NUM> in communication with the controller <NUM>. The oxygen sensor <NUM> and/or carbon dioxide sensor <NUM> may be located in the evaporator section <NUM>, upstream of the evaporator <NUM>. To add outside air to the container, the controller <NUM> sends a signal to turn on the air compressor <NUM> and sends a signal to the first valve V1 to set the first valve V1 to the open position. This directs the compressed air from the air compressor <NUM> to the interior of the container <NUM>. To add nitrogen to the container to control the levels of other gasses, the controller <NUM> sends a signal to turn on the air compressor <NUM> and closes valve V1. This directs the compressed air from the air compressor <NUM> to the separator <NUM>, which produces nitrogen that is directed to the interior of the container <NUM> (e.g., upstream or downstream of the evaporator <NUM>). To measure purity of the nitrogen generated by the separator <NUM>, the controller <NUM> opens the bleeder port of the second valve V2 to direct a portion of the nitrogen to the nitrogen sensor <NUM> in communication with the controller <NUM>. Optionally, a separate nitrogen sensor <NUM> is not used, as the measurements from the oxygen sensor <NUM> provides an indication of the nitrogen level in the container <NUM>.

<FIG> depicts the atmosphere control system <NUM>' in a variation of the above. The arrangement of <FIG> is similar to that of <FIG>, with the exception that second filter <NUM> and third filter <NUM> are located in the evaporator section <NUM>, rather than in the condenser section <NUM>. Operation of the atmosphere control system <NUM>' is similar to that of <FIG>.

Positioning the air compressor <NUM> in the condenser section <NUM> allows use of an air compressor not requiring an enclosed motor and enclosed crankcase, thereby allowing some acceptable amount of air blow (i.e., air leakage due to pressure and movement of the cylinders) from compressor crankcase. If a non-enclosed compressor was placed inside in the evaporator section, air blow from the compressor crankcase would directly impact system performance by not allowing proper control of oxygen. Positioning the air compressor <NUM> in the condenser section <NUM> also provides easier access for maintenance on the air compressor <NUM>. A removable shield or plate can be used to protect the air compressor <NUM> from outside elements such as water and dirt, since the air compressor is located in the condenser section <NUM> and not inside the container <NUM>. The atmosphere control system <NUM> is controlled by the same controller <NUM> used to control the refrigeration unit <NUM>, or by a separate controller.

Claim 1:
A refrigeration unit (<NUM>) for use with a container (<NUM>), the refrigeration unit comprising:
a compressor (<NUM>), a condenser (<NUM>), an expansion device (<NUM>) and an evaporator (<NUM>) configured to circulate a refrigerant;
a condenser section (<NUM>) housing the compressor and the condenser;
an evaporator section (<NUM>) housing the evaporator; and
an atmosphere control system (<NUM>, <NUM>') comprising: an air compressor (<NUM>) configured to generate compressed air, the air compressor located outside the container; a separator (<NUM>) configured to receive the compressed air and output nitrogen into the interior of the container; a valve (V1) between the air compressor (<NUM>) and the separator (<NUM>); a heat exchanger (<NUM>) positioned between the air compressor (<NUM>) and the separator (<NUM>), the heat exchanger configured to cool the compressed air from the air compressor; and a water separator (<NUM>) between the heat exchanger (<NUM>) and the separator (<NUM>); wherein, the valve (V1), in an open position, directs compressed air to the container (<NUM>); wherein the air compressor is located in the condenser section; and wherein the separator is located in the evaporator section.