Patent Description:
The transportation refrigeration vehicles used in existing cold chain transportation generally use mechanical refrigeration devices. In order to reduce the temperature inside the cargo box to a set temperature quickly, the mechanical refrigeration device needs to have a large refrigeration capacity. Therefore, the mechanical refrigeration device itself and the devices that power it, such as combustion engines, lithium batteries, or fuel cells, need to be designed with a larger volume and weight.

On the other hand, liquid nitrogen refrigeration systems can achieve rapid cooling, but their cost is high and they are not suitable for long-distance transportation. <CIT> describes a refrigeration system of a refrigerated truck wherein the truck carriage has a heat pump refrigeration unit and an additional liquid nitrogen refrigeration device,.

The object of the present application is to solve or at least alleviate the problems existing in the prior art.

According to a first aspect of the invention there is provided, a hybrid refrigeration system for a transportation refrigeration vehicle is provided, comprising:.

Optionally, when the first refrigeration device is started and the set temperature is reached, or when the difference between the temperature of the cargo box and the set temperature is less than the first threshold, the first refrigeration device is turned off and the second refrigeration device is used to maintain the temperature of the cargo box. Optionally, a selectable range of the first threshold is, for example, <NUM> -<NUM>, such as <NUM> -<NUM>.

Optionally, the first refrigeration device comprises a liquid nitrogen storage tank and a liquid nitrogen release control valve, where the first refrigeration device regulates the temperature of the cargo box by converting liquid nitrogen into nitrogen gas and transporting it to the cargo box, or the first refrigeration device further comprises a first cargo box heat exchanger, where the first refrigeration device regulates the temperature of the cargo box by converting the liquid nitrogen into nitrogen gas, passing it through the first cargo box heat exchanger and then discharging it to the environment.

Optionally, the second refrigeration device comprises a compressor, a condenser, a throttling device, and a second cargo box heat exchanger.

Optionally, the second refrigeration device is powered by a combustion engine, a lithium battery, or fuel cells.

Optionally, the first refrigeration device and the second refrigeration device share the same cargo box heat exchanger.

Optionally, in the event of a failure of either the first refrigeration device or the second refrigeration device, the other of the first refrigeration device or the second refrigeration device alone serves as a backup refrigeration device for temperature regulation of the cargo box.

According to a second aspect of the invention there is provided, a transportation refrigeration vehicle comprising a hybrid refrigeration system according to the various embodiments is provided, wherein the transportation refrigeration vehicle is powered by a combustion engine, a lithium battery, or fuel cells, where the hybrid refrigeration system and the transportation refrigeration vehicle share an energy supply device or respectively comprise independent energy supply devices.

According to a third aspect of the invention, a control method for a hybrid refrigeration system is further provided, comprising:.

Optionally, the method further comprises: turning off the first refrigeration device and using the second refrigeration device to maintain the temperature of the cargo box when the first refrigeration device is started and the set temperature is reached, or when the difference between the temperature of the cargo box and the set temperature is less than the first threshold. Optionally, a selectable range of the first threshold is, for example, <NUM> -<NUM>, such as <NUM> -<NUM>.

The device and method according to the embodiments of the present invention can reduce the requirement for the capacity of the mechanical refrigeration device on the vehicle, and thus reduce the weight and volume of the mechanical refrigeration device.

With reference to the accompanying drawings, the disclosure of the present application will become easier to understand. Those skilled in the art would easily understand that these drawings are for the purpose of illustration, and are not intended to limit the protection scope of the present application. In addition, in the figures, similar numerals are used to denote similar components, where:.

A hybrid refrigeration system for a transportation refrigeration vehicle according to various embodiments of the present invention will first be described in conjunction with <FIG>. The transportation refrigeration vehicle can be used for cold chain transportation, including food, drugs, and the like, which mainly comprise a tractor <NUM>, a trailer <NUM>, and a cargo box <NUM> arranged on a platform defined by the tractor <NUM> and the trailer <NUM>, with its interior used to store goods that need cold chain transportation. In addition, the transportation refrigeration vehicle also comprises a hybrid refrigeration system according to various embodiments of the present invention.

The hybrid refrigeration system according to the embodiment shown in <FIG> comprises: a first refrigeration device <NUM> for regulating the temperature of the cargo box <NUM>, where the first refrigeration device <NUM> is a liquid nitrogen based refrigeration device; a second refrigeration device <NUM> for regulating the temperature of the cargo box <NUM>, where the second refrigeration device <NUM> is a mechanical refrigeration device; and a controller connected to the first refrigeration device <NUM> and the second refrigeration device <NUM>; wherein, the controller is configured to determine whether the difference between the temperature of the cargo box and a set temperature is greater than or equal to a first threshold when receiving a refrigeration demand for the cargo box; if so, start the first refrigeration device <NUM> alone or start both the first refrigeration device <NUM> and the second refrigeration device <NUM> simultaneously; and if not, start the second refrigeration device <NUM> alone. By using this hybrid refrigeration system, the first refrigeration device <NUM> based on liquid nitrogen can be used to reduce the temperature of the cargo box quickly when the difference between the temperature of the cargo box and the set temperature is large, while the second refrigeration device <NUM> is used to assist in cooling and maintaining temperature. This reduces the requirement for the refrigeration capacity of the second refrigeration device <NUM>, thereby reducing the weight of various components of the second refrigeration device <NUM> based on mechanical refrigeration as well as the weight of the energy supply devices that power them. When the difference between the temperature of the cargo box and the set temperature is small, there is no need to start the first refrigeration device <NUM> and the second refrigeration device <NUM> is used to achieve temperature regulation. In some embodiments, the selectable range of the first threshold is, for example, <NUM> -<NUM>, and optionally, between, for example, <NUM> -<NUM>.

In some embodiments, the controller may be further configured to turn off the first refrigeration device <NUM> and use the second refrigeration device <NUM> to maintain the temperature of the cargo box when using the first refrigeration device <NUM> and the temperature of the cargo box is reduced to the set temperature. In alternative embodiments, the controller can otherwise be configured to turn off the first refrigeration device <NUM> when the difference between the temperature of the cargo box and the set temperature is less than the first threshold, and then the second refrigeration device <NUM> alone regulates the temperature of the cargo box. In the case of using the first refrigeration device <NUM> for cooling, the second refrigeration device <NUM> can be turned on at any time after receiving the refrigeration demand but before the first refrigeration device <NUM> being turned off. For example, the second refrigeration device <NUM> can be turned on simultaneously with the first refrigeration device <NUM> to achieve the fastest cooling, or turned on when the first refrigeration device <NUM> is turned off, thereby saving energy. In the device according to the present invention, as the second refrigeration device <NUM> is only used for maintaining temperature and a small load of cooling, the rated capacity, weight, and volume of the second refrigeration device <NUM> can be reduced compared to conventional mechanical refrigeration devices. In addition, the time required to lower the temperature of the cargo box to its set point when the refrigeration device is first started can also be reduced.

In some embodiments, the first refrigeration device <NUM> comprises a liquid nitrogen storage tank <NUM>, a liquid nitrogen storage sink <NUM>, a liquid nitrogen release control valve <NUM>, a liquid nitrogen transfer pipeline <NUM>, and a first cargo box heat exchanger <NUM>. In the embodiment shown in <FIG>, the first refrigeration device <NUM> regulates the temperature of the cargo box by converting the liquid nitrogen in the liquid nitrogen storage tank <NUM> into a gaseous state through the control valve <NUM>, and exchanging heat with the air in the cargo compartment through the first cargo box heat exchanger <NUM> and then discharging it into the environment. With continued reference to <FIG>, in an alternative embodiment, the first refrigeration device <NUM> can regulate the temperature of the cargo box by converting the liquid nitrogen into a gaseous state through the control valve <NUM> and directly transporting it to the interior of the cargo box <NUM>. In such an embodiment, several pipelines and nozzles can also be arranged to allow nitrogen gas to enter the cargo box <NUM> more evenly. In the embodiment illustrated, the liquid nitrogen storage tank <NUM> of the first refrigeration device <NUM> is arranged in the trailer <NUM> below the cargo box <NUM>, and the trailer <NUM> may comprise a liquid nitrogen replenishment interface to replenish liquid nitrogen at the station, or the liquid nitrogen storage tank <NUM> may be replaced after the journey is completed.

In some embodiments, the second refrigeration device <NUM> may comprise a compressor, a condenser, a throttling device, and a second cargo box heat exchanger <NUM> connected into a circulating circuit. That is, the second refrigeration device <NUM> comprises a traditional refrigeration circuit comprising a compressor. In the embodiment of <FIG>, the second refrigeration device <NUM> is powered by a lithium battery <NUM>. In alternative embodiments, fuel cells can also be used to replace the lithium battery <NUM>. Or, as shown in <FIG>, the second refrigeration device <NUM> can be powered by a traditional combustion engine. As mentioned above, due to the addition of the first refrigeration device <NUM> based on liquid nitrogen, the capacity of components, such as the compressor, in the second refrigeration device <NUM> can be reduced, and their weight and volume can also be reduced. In addition, the weight and volume of the lithium battery <NUM> that powers the second refrigeration device <NUM> can also be reduced, which is crucial for vehicles powered by new energy sources such as lithium batteries, as the reduced weight means longer range. For example, as shown in <FIG>, the tractor <NUM> may include an additional lithium battery or fuel cells <NUM>, which can help to achieve a longer range for the transportion refrigeration vehicle when the weight of the second refrigeration device <NUM> is reduced. In some embodiments, the second refrigeration device <NUM> may be arranged at the front of the cargo box <NUM>, and the energy supply device <NUM> thereof may also be arranged in the trailer <NUM>.

As shown in <FIG>, in some embodiments, the first refrigeration device <NUM> and the second refrigeration device <NUM> may also share the same cargo box heat exchanger <NUM>. The cargo box heat exchanger <NUM> may comprise a first flow path for discharging nitrogen gas into the environment and a second flow path for the refrigerant in the second refrigeration device <NUM>, as well as a fan for facilitating heat exchange between the air in the cargo box and the nitrogen gas in the first flow path and the refrigerant in the second flow path. The pipeline <NUM> of the first refrigeration device can be connected to the first flow path. In addition, in some embodiments, the first refrigeration device <NUM> and the second refrigeration device <NUM> can serve as backup refrigeration systems for each other. That is, in the event of a failure of either the first refrigeration device <NUM> or the second refrigeration device <NUM>, the other of the first refrigeration device <NUM> and the second refrigeration device <NUM> can alone serve as a backup refrigeration device for temperature regulation of the cargo box. That is, the controller is configured to use the one in normal operation to regulate the temperature inside the cargo box <NUM> in the event of a failure of the first refrigeration device <NUM> or the second refrigeration device <NUM>, thus allowing the hybrid refrigeration system to cope with the failure of a single refrigeration device and try to preserve important goods being transported in the cargo box.

According to another aspect, for a transportation refrigeration vehicle, it may include a hybrid refrigeration system according to any of the above embodiments. The transportation refrigeration vehicle may be driven by a combustion engine, a lithium battery, or fuel cells, wherein the hybrid refrigeration system and the transportation refrigeration vehicle may share the combustion engine, the lithium battery, or the fuel cells, or they may have independent energy supply devices.

With continued reference to <FIG>, a control method for a hybrid refrigeration system according to an embodiment of the present invention will be described. The control method may comprise: S0: receiving a refrigeration demand for a cargo box; S1: determining whether the difference between the temperature of the cargo box and a set temperature is greater than or equal to a first threshold; if not, proceed to step S2 to start the second refrigeration device alone; and if yes, proceed to step S3 to start the first refrigeration device based on liquid nitrogen alone or start both the first refrigeration device based on liquid nitrogen and the second refrigeration device based on mechanical refrigeration simultaneously. In some embodiments, the method further comprises: step S4: turning off the first refrigeration device and using the second refrigeration device to maintain the temperature of the cargo box when the first refrigeration device is started and the set temperature is reached, or when the difference between the temperature of the cargo box and the set temperature is less than the first threshold. Optionally, the selectable range of the first threshold is, for example, <NUM> -<NUM>, such as between <NUM> -<NUM>.

Claim 1:
A hybrid refrigeration system for a transportation refrigeration vehicle, comprising:
a first refrigeration device (<NUM>) for regulating a temperature of a cargo box (<NUM>) of the transportation refrigeration vehicle, wherein the first refrigeration device is a liquid nitrogen based refrigeration device; and
a second refrigeration device (<NUM>) for regulating the temperature of the cargo box of the transportation refrigeration vehicle, wherein the second refrigeration device is a mechanical refrigeration device;
a controller connected to the first refrigeration device and the second refrigeration device;
wherein, the controller is configured to determine whether a difference between the temperature of the cargo box and a set temperature is greater than or equal to a first threshold when receiving a refrigeration demand for the cargo box;
if so, start the first refrigeration device alone or start both the first refrigeration device and the second refrigeration device simultaneously; and
if not, start the second refrigeration device alone.