Patent Description:
Refrigeration systems are known. Generally, a compressor compresses a refrigerant and delivers it into a condenser. The refrigerant is cooled and passes through an expansion valve. The refrigerant is expanded and passes through an evaporator. The evaporator cools air to be delivered into an environment to be conditioned.

One application for such refrigeration systems is in a transportation refrigeration system. As an example, a truck may have a refrigerated trailer. It is known to provide distinct temperatures at distinct compartments within a common trailer. Individual refrigeration circuits are often utilized to provide the distinct temperatures.

<CIT> discloses an air conditioner that makes a judgment as to whether or not the amount of refrigerant in a refrigerant circuit is adequate. A vapor compression-type refrigerant circuit of the air conditioner is formed by the interconnection of an outdoor unit, two indoor units, a liquid refrigerant communication pipe and a gaseous refrigerant communication pipe. The outdoor unit is a heat source unit, and the indoor units are utilization units connected in parallel to the outdoor unit. The indoor units each comprise an indoor side refrigerant circuit, which includes an indoor expansion valve as an expansion mechanism and an indoor heat exchanger as a utilization side heat exchanger. The indoor expansion valve is an electric expansion valve connected to the liquid side of the indoor heat exchanger in order to adjust the flow rate or the like of the refrigerant flowing in the indoor side refrigerant circuit.

<CIT> discloses a refrigeration apparatus comprising a refrigerant circuit including a heat source unit having a compressor and a plurality of utilization units having a utilization side heat exchanger and arranged in parallel with each other. A plurality of inlet valves are configured and arranged to cut off a flow of supplied refrigerant in a closed state and each of the inlet valves is disposed on a refrigerant inlet side of any of the utilization-side heat exchangers. A control unit is connected to refrigerant leakage sensors for detecting leakage of refrigerant in each of the units to control these inlet valves.

From a first aspect, there is provided a transportation refrigeration system comprising: a single distinct compartment to be conditioned; a refrigeration circuit associated with an enclosure including a compressor, a condenser, an expansion valve upstream of a first evaporator, a first evaporator inlet shut-off valve, a first evaporator outlet shut-off valve, a second evaporator, a second evaporator inlet shut-off valve and a second evaporator outlet shut-off valve, wherein the first evaporator is in parallel with the second evaporator, wherein when the first evaporator inlet and outlet shut-off valves are closed, the first evaporator becomes fluidly isolated from the rest of the refrigeration circuit, and when the second evaporator inlet and outlet shut-off valves are closed, the second evaporator becomes fluidly isolated from the rest of the refrigeration circuit; a first enclosure surrounding the first evaporator, wherein the first enclosure includes a first refrigerant detection sensor in communication with a controller; and a second enclosure surrounding the second evaporator, wherein the second enclosure includes a second refrigerant detection sensor in communication with the controller; wherein the first refrigerant detection sensor is configured to identify the presence of refrigerant in an atmosphere of the first enclosure and the second refrigerant detection sensor is configured to identify the presence of refrigerant in an atmosphere of the second enclosure; and wherein the isolating function of the first evaporator inlet and outlet shut-off valves and the second evaporator inlet and outlet shut-off valves allows a non-isolated evaporator to continue to function in the refrigeration circuit; characterised in that the first and second evaporator condition the single distinct compartment.

In a further embodiment of any of the above, the first enclosure includes a first refrigerant detection sensor in communication with the controller.

In a further embodiment of any of the above, the second enclosure includes a second refrigerant detection sensor in communication with the controller.

In a further embodiment of any of the above, the refrigeration circuit includes a first fan directed at the first evaporator.

In a further embodiment of the previous embodiment, the refrigeration circuit includes a second fan directed at the second evaporator.

In a further embodiment of any of the above, the first fan and the second fan are independently operable.

In a further embodiment of any of the above, the first evaporator inlet shut-off valve, the first evaporator outlet shut-off valve, the second evaporator inlet shut-off valve and the second evaporator outlet shut-off valve are solenoid valves in communication with the controller.

In a further embodiment of any of the above, the first enclosure is separated from the second enclosure by a bulkhead.

In a further embodiment of any of the above, the first evaporator inlet shut-off valve, the first evaporator outlet shut-off valve, the second evaporator inlet shut-off valve and the second evaporator outlet shut-off valve are located outside of the compartment.

From a second aspect, the present invention provides a method of operating a refrigeration cycle comprising the steps of conditioning a single distinct compartment with a refrigeration circuit to a first temperature, wherein the refrigeration circuit includes a compressor, a condenser, an expansion valve upstream of a first evaporator, a first evaporator inlet shut-off valve, a first evaporator outlet shut-off valve, a second evaporator, a second evaporator inlet shut-off valve and a second evaporator outlet shut-off valve, wherein the first evaporator is in parallel with the second evaporator, wherein when the first evaporator inlet and outlet shut-off valves are closed, the first evaporator becomes fluidly isolated from the rest of the refrigeration circuit, and when the second evaporator inlet and outlet shut-off valves are closed, the second evaporator becomes fluidly isolated from the rest of the refrigeration circuit; detecting a refrigerant leak in a first enclosure including the first evaporator with a first refrigerant sensor; and isolating the first evaporator from the refrigerant circuit by closing the first evaporator inlet shut-off valve and the first evaporator outlet shut-off valve, wherein the isolating function of the first evaporator inlet and outlet shut-off valves allows the non-isolated second evaporator to continue to function in the refrigeration circuit; wherein the first refrigerant sensor identifies the presence of refrigerant in the atmosphere of the first enclosure; characterised in that the first and second evaporator condition the single distinct compartment.

In a further embodiment of any of the above, the method includes disabling a first fan located adjacent the first evaporator upon detecting a refrigerant leak in the first enclosure.

In a further embodiment of any of the above, the method includes conditioning the compartment with only the second evaporator to a second temperature greater than the first temperature.

In a further embodiment of any of the above, the method includes detecting a refrigerant leak in a second enclosure which includes the second evaporator with a second refrigerant sensor.

In a further embodiment of any of the above, the method includes isolating the second evaporator from the refrigerant circuit by closing a second evaporator inlet shut-off valve and a second evaporator outlet shut-off valve.

In a further embodiment of any of the above, the method includes disabling a second fan located adjacent the second evaporator upon detecting a refrigerant leak in the second enclosure.

In a further embodiment of any of the above, the method includes providing equal amounts of conditioning with the first evaporator and the second evaporator to the compartment.

These and other features of the disclosed examples can be understood from the following description and the accompanying drawings, which can be briefly described as follows.

<FIG> schematically shows a refrigeration transportation system.

<FIG> illustrates a refrigerated system <NUM>. As known, the refrigerated system <NUM> may be a refrigerated cargo compartment associated with a truck or another type of refrigerated cargo system, such as a trailer, a shipboard container, etc. In the illustrated non-limiting example, the refrigerated system <NUM> includes a single distinct compartment <NUM> that is conditioned. The single distinct compartment <NUM> is maintained at a single temperature level during normal operating conditions. A refrigeration circuit <NUM> is provided to maintain the single distinct compartment <NUM> at the desired operating temperature.

The refrigeration circuit <NUM> includes a compressor <NUM> that compresses and delivers a refrigerant, such as low GWP refrigerant, to a condenser <NUM> located downstream of the compressor <NUM>. The condenser <NUM> removes heat from the refrigerant. Downstream of the condenser <NUM>, the refrigerant passes through an expansion device <NUM>. The expansion device <NUM> may be an electronic expansion device which is capable of being controlled to open to any number of varying positions after receiving commands from a controller <NUM>.

A first evaporator <NUM> and a second evaporator <NUM> are located downstream of the expansion device <NUM>. The first and second evaporators <NUM>, <NUM> are fluidly in parallel with each other such that the refrigerant will pass through only one of the first and second evaporators <NUM>, <NUM> during each loop through the refrigeration circuit <NUM>. This allows the first and second evaporators <NUM>, <NUM> to provide equal amounts of cooling. After the refrigerant passes through the first and second evaporators <NUM>, <NUM>, the refrigerant will travel back to the compressor <NUM> and through the refrigeration circuit <NUM> again.

The first and second evaporators <NUM> and <NUM> condition the single distinct compartment <NUM> to the desired temperature by transferring heat from the single distinct compartment <NUM> into the refrigerant. The first and second evaporators <NUM>, <NUM> are aided in transferring heat from the environment of the single distinct compartment <NUM> into the refrigerant by a first fan <NUM> and a second fan <NUM>, respectively.

The first fan <NUM> and the first evaporator <NUM> are located in a first enclosure <NUM> and the second fan <NUM> and the second evaporator <NUM> are located in a second enclosure <NUM>. The first and second enclosures <NUM>, <NUM> are separated from each other by a bulkhead <NUM>. The first and second enclosures <NUM>, <NUM> include first and second enclosure inlets <NUM>, <NUM> and first and second enclosure outlets <NUM>, <NUM>, respectively. The first and second enclosures <NUM>, <NUM> allow air from the single distinct compartment <NUM> to flow over the first and second evaporators <NUM>, <NUM>, respectively, while fluidly separating the air in each of the first and second enclosures <NUM>, <NUM> from each other.

During operation of the refrigeration circuit <NUM>, the refrigerant travels in a loop through the compressor <NUM>, the condenser <NUM>, the expansion device <NUM>, and the first and second evaporators <NUM>, <NUM>. While operating the refrigeration circuit <NUM>, it is possible that a refrigerant leak may develop in one or both of the first and second evaporators <NUM>, <NUM> or with adjacent connections to the first and second evaporators <NUM>, <NUM> in the first and second enclosure <NUM>, <NUM>, respectively.

A refrigerant leak in either of the first or second evaporators <NUM>, <NUM> or in the surrounding structure will be detected by either a first refrigerant sensor <NUM> located in the first enclosure <NUM> or a second refrigerant sensor <NUM> located in the second enclosure <NUM>. In the illustrated non-limiting example, the first and second refrigerant sensors <NUM>, <NUM> are located in the first and second enclosures <NUM>, <NUM>, adjacent the first and second enclosure outlets <NUM>, <NUM>, respectively, in order to be exposed to a greater amount of fluid traveling through the first and second enclosures <NUM>, <NUM>. The first and second refrigerant sensors <NUM>, <NUM> detect the presence of refrigerant in the atmosphere of the first and second enclosures, <NUM>, <NUM>.

When a refrigerant leak is detected by the first refrigerant sensor <NUM>, a signal is sent to the controller <NUM> and the controller <NUM> sends a signal to close a first evaporator inlet shut-off valve <NUM> and a first evaporator outlet shut-off valve <NUM> in the refrigeration circuit <NUM>. The controller <NUM> also sends a signal to stop the first fan <NUM> when shutting the first evaporator inlet and outlet shut-off valves <NUM>, <NUM>. By closing the first evaporator inlet and outlet shut-off valves <NUM>, <NUM>, which are located outside of the single distinct compartment <NUM>, the amount of refrigerant that can leak into the single distinct compartment <NUM> is limited to the amount of refrigerant located between the first evaporator inlet and outlet shut-off valves <NUM>, <NUM>. When the first evaporator inlet and outlet shut-off valves <NUM>, <NUM> are closed, the first evaporator <NUM> becomes fluidly isolated from the rest of the refrigeration circuit <NUM>.

Similarly, when a refrigerant leak is detected by the second refrigerant sensor <NUM>, a signal is sent to the controller <NUM> and the controller <NUM> sends a signal to close a second evaporator inlet shut-off valve <NUM> and a second evaporator outlet shut-off valve <NUM> in the refrigeration circuit <NUM>. The controller <NUM> also sends a signal to stop the second fan <NUM> when shutting the second evaporator inlet and outlet shutoff valves <NUM>, <NUM>. By closing the second evaporator inlet and outlet shut-off valves <NUM>, <NUM>, which are located outside of the single distinct compartment <NUM>, the amount of refrigerant that can leak into the single distinct compartment <NUM> is limited to the amount of refrigerant located between the second evaporator inlet and outlet shut-off valves <NUM>, <NUM>. When the second evaporator inlet and outlet shut-off valves <NUM>, <NUM> are closed, the second evaporator <NUM> becomes fluidly isolated from the rest of the refrigeration circuit <NUM>.

In the illustrated example, the first evaporator inlet and outlet shut-off valves <NUM>, <NUM> and the second evaporator inlet and outlet shut-off valves <NUM>, <NUM> are solenoid valves. However, other types of valves could be used in place of the solenoid valves.

The isolating function of the first evaporator inlet and outlet shut-off valves <NUM>, <NUM> and the second evaporator inlet and outlet shut-off valves <NUM>, <NUM> allows the non-isolated evaporator to continue to function in the refrigeration circuit <NUM> and maintain the single distinct compartment <NUM> desired operating temperature. If the single compartment <NUM> desired operating temperature cannot be maintained due to operating at a reduced capacity with only a single evaporator, the amount of time before the single distinct compartment <NUM> reaches a temperature that is undesirable for the goods in the single distinct compartment <NUM> is extended such that the chance of damaging the goods is reduced. If the refrigeration circuit <NUM> enters any of the isolation modes discussed above, the controller <NUM> will provide an alarm or display a message indicating that a leak has occurred.

Moreover, in the case that a refrigerant leak is detected by both the first refrigerant leak sensor <NUM> and the second refrigerant sensor <NUM>, both the first and second evaporators <NUM>, <NUM> would become fluidly isolated from the rest of the refrigeration circuit <NUM>. This would result in the refrigeration circuit <NUM> no longer being able to function.

Claim 1:
A transportation refrigeration system (<NUM>) comprising:
a single distinct compartment to be conditioned (<NUM>);
a refrigeration circuit (<NUM>) associated with an enclosure including a compressor (<NUM>), a condenser (<NUM>), an expansion valve (<NUM>) upstream of a first evaporator (<NUM>), a first evaporator inlet shut-off valve (<NUM>), a first evaporator outlet shut-off valve (<NUM>), a second evaporator (<NUM>), a second evaporator inlet shut-off valve (<NUM>) and a second evaporator outlet shut-off valve (<NUM>), wherein the first evaporator is in parallel with the second evaporator, wherein when the first evaporator inlet and outlet shut-off valves (<NUM>, <NUM>) are closed, the first evaporator (<NUM>) becomes fluidly isolated from the rest of the refrigeration circuit (<NUM>), and when the second evaporator inlet and outlet shut-off valves (<NUM>, <NUM>) are closed, the second evaporator (<NUM>) becomes fluidly isolated from the rest of the refrigeration circuit (<NUM>);
a first enclosure (<NUM>) surrounding the first evaporator, wherein the first enclosure includes a first refrigerant detection sensor (<NUM>) in communication with a controller (<NUM>); and
a second enclosure (<NUM>) surrounding the second evaporator, wherein the second enclosure includes a second refrigerant detection sensor (<NUM>) in communication with the controller;
wherein the first refrigerant detection sensor (<NUM>) is configured to identify the presence of refrigerant in an atmosphere of the first enclosure (<NUM>) and the second refrigerant detection sensor (<NUM>) is configured to identify the presence of refrigerant in an atmosphere of the second enclosure (<NUM>);
wherein the isolating function of the first evaporator inlet and outlet shut-off valves (<NUM>, <NUM>) and the second evaporator inlet and outlet shut-off valves (<NUM>, <NUM>) allows a non-isolated evaporator to continue to function in the refrigeration circuit (<NUM>); and
wherein the first and second evaporator condition the single distinct compartment.