The embodiments disclosed herein relate generally to a transport refrigeration system (TRS). More particularly, the embodiments relate to methods and systems for controlling the operation of the condenser and evaporator fans in a TRS.
Existing transport refrigeration systems are used to cool containers, trailers, railcars or other transport units. A temperature controlled transport unit (typically referred to as a “refrigerated transport unit”) is commonly used to transport perishable items such as produce and meat products. In such a case, a TRS can be used to condition the air inside a cargo space of the transport unit, thereby maintaining desired temperature and humidity settings during transportation or storage. Typically, a transport refrigeration unit (“TRU”) is attached to the transport unit to facilitate a heat exchange between the air inside the cargo space and the air outside of the transport unit.
The embodiments described herein are directed to a TRS. In particular, the embodiments described herein are directed to methods and systems for controlling the operation of the condenser and evaporator fans in the TRS.
The methods and systems described herein generally control dynamically a plurality of system fans needed to meet a plurality of system requirements which may sometimes conflict. The methods and systems described herein can be used to strike an optimal balance between system performance, protection, safety and regulatory requirements.
Generally, the methods and systems described herein can achieve optimal performance and system protection with precise control of airflow across a set of one or more evaporators and airflow across a set of two or more condensers, while meeting regulatory requirements (e.g., mandated Environmental Protection Agency (EPA) emissions limit requirements) with optimized intercooler airflow requirements. System protection can be achieved by maintaining engine operation within a defined set of engine operation parameters. Such operating parameters can include, for example, not exceeding engine power capacity per time slice, providing adequate engine cooling needed to meet performance and durability requirements, and not exceeding generator ability. The methods and systems described herein can lead to a reduced initial cost of the system and total cost of ownership of the system. These are achieved through the use of fewer hardware components such as fans (reduced complexity), less weight of the system, and less costs during operation, e.g., due to fuel savings and increased system performance.
In some embodiments, the systems and methods described herein provides for controlling the operation of at least two condenser fans based on the difference between a coil temperature (e.g., discharge pressure temperature saturation) and an ambient temperature and controlling the operation of at least one evaporator fan based on an air temperature differential.
In one embodiment of the process of controlling the operation of the condenser and the evaporator fans, a plurality of parameters are determined. In one example, the parameters include a discharge pressure temperature saturation (DPTSAT), a minimum discharge pressure (DPMIN), an ambient temperature (AT), an engine coolant temperature (ECT), an engine intercooler temperature (EICT), an engine cooling fan request (ECFR), an engine intercooler fan request (EIFR), and a box temperature (BT). Then, a determination is made as to whether there is a conflict between the determined parameters and a set of predetermined operating conditions.
If there is a conflict, then the condenser and the evaporator fans operate based on the set of predetermined operating conditions. If there is no conflict, then the condenser and the evaporator fans operate in a certain state of operation, e.g., on state, off state, high speed, low speed, or continuously varying speed, based on certain predetermined conditions.
In one example, when the difference between the determined DPTSAT and the AT (T1) is greater than a first predetermined value, a first condenser fan is turned on. When a second predetermined value is greater than second predetermined value, a second condenser fan is turned on. When the determined ECT is greater than a third predetermined value, the first condenser fan and/or the second condenser fan are turned on.
In another example, when the determined ECT is less than a fifth predetermined value, the first condenser fan is turned off. When the determined ECT is less than the fifth predetermined value, the second condenser is turned off.
In yet another example, when the difference between a box temperature and a target temperature (T2) is greater than a seventh predetermined value, the evaporator fan operates at high speed. When T2 is less than an eight predetermined value, the evaporator fan operates at low speed.
In some embodiments, the condenser fans are single speed fans and the evaporator fan(s) is a dual speed fan. In other embodiments, the condenser fans and the evaporator fan(s) are variable speed condenser fans.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
Referring now to the drawings in which like reference numbers represent corresponding parts throughout.
The embodiments described herein are directed to a transport refrigeration system (TRS). More particularly, the embodiments relate to methods and systems for controlling the operation of the condenser and evaporator fans in a TRS.
References are made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration of the embodiments in which the methods and systems described herein may be practiced. The term “refrigerated transport unit” generally refers to, for example, a conditioned trailer, container, railcars or other type of transport unit, etc. The term “transport refrigeration system” or “TRS” refers to a refrigeration system for controlling the refrigeration of a conditioned interior space of the refrigerated transport unit. The term “TRS controller” refers to an electronic device that is configured to manage, command, direct and regulate the behavior of one or more TRS refrigeration components of a refrigeration circuit (e.g., an evaporator, a condenser, a compressor, an expansion valve (EXV), etc.), a genset, etc.
It will be appreciated that the embodiments described herein may be used in any suitable temperature controlled apparatus such as a ship board container, an air cargo cabin, an over the road truck cabin, etc. The TRS may be a vapor-compressor type refrigeration system, or any other suitable refrigeration system that can use refrigerant, cold plate technology, etc.
As shown in
Each of the two condenser fans 144a, 144b is configured to discharge air out of the TRU 140 in a vertically upward direction as shown by arrows 146. The condenser fans 144a, 144b shown in
In one embodiment, the condenser fans 144a, 144b are axial fans. In other embodiments, the condenser fans 144a, 144b can be any type of that is suitable for moving air in the TRS 120, and can include, but is not limited to vane axial fans, radial fans, etc.
In some embodiments, the speed (e.g., rpm) of the condenser fans 144a, 144b can be frequency controlled based on a speed of an engine of a TRS genset. For example, in one embodiment, the condenser fans 144a, 144b can operate at ˜2650 rpm when the engine is operating at ˜2050 rpm and can operate at ˜1620 rpm when the engine is operating at ˜1250 rpm. It is to be realized that in other embodiments, the fan motor speed can vary as desired.
In other embodiments, the condenser fans 144a, 144b can be two-speed condenser fans that are configured to be electronically controlled by the TRS Controller 220 to operate at a high speed and a low speed. In these embodiments, for example, the high speed of the condenser fans 144a, 144b can be ˜2650 rpm and the low speed of the condenser fans 144a, 144b can be ˜1620 rpm. It is to be realized that in other embodiments, the engine speed and the fan motor speed can vary as desired.
In yet some other embodiments, the condenser fans 144a, 144b are variable speed condenser fans, whereby the speed of the condenser fans 144a, 144b can be electronically controlled by the TRS Controller 220.
Referring to
In some embodiments, the evaporator fan 147 can be a multi-speed fan that is configured to operate at a continuously varying speed. In some examples, the evaporator fan 147 is a two speed evaporator fan that operates at a high speed or a low speed. In these embodiments, the high speed of the evaporator fan 147 can be ˜1750 rpm. The low speed of the evaporator fan 147 can be ˜1400 rpm.
The TRU 140 is configured to be in communication with the internal space 150 and is also configured to control the temperature in the internal space 150. The components within the TRU 140 are described below with reference to
Generally, as illustrated in
Examples of different configurations of the condenser fans 144a, 144b, the evaporator fan 147, the radiator 212 and/or the intercooler 218 will now be described with reference to
In another example as shown in
With reference to
With reference to
With reference to
Generally, the TRS Controller 220 is configured to control a refrigerant circuit 240 that includes the condenser 162, the expansion valve 205, the evaporator 194 and the compressor 183. In one example, the TRS Controller 220 controls the operating states of each of the condenser fans 144a, 144b and the evaporator fan 147. In another example, the TRS Controller 220 controls the refrigeration circuit 240 to obtain various operating conditions (e.g., temperature, humidity, etc.) of the internal space 150 as is generally understood in the art. The refrigeration circuit 240 regulates various operating conditions (e.g., temperature, humidity, etc.) of the internal space 150 based on instructions received from the TRS Controller 220.
In one example, during operation, the TRS Controller 220 receives information from the plurality of sensors 222 through the I/O interface 223 as inputs, processes the received information using the processor based on an algorithm stored in the memory, and then send command signals as outputs, to the condenser fans 144a, 144b and the evaporator fan 147. A summary of the inputs and outputs are illustrated in
Details of the inputs that are received by the TRS Controller 220 will now be described. The inputs that are received by the TRS Controller 220 include data of parameters that are typically received when operating the TRS 120, such as a discharge pressure temperature saturation (DPTSAT), a minimum pressure temperature saturation (MPTSAT), a minimum discharge pressure (DPMIN), an ambient temperature (AT); an engine coolant temperature (ECT), an engine intercooler temperature (EICT), an engine cooling fan request (ECFR), an engine intercooler fan request (EIFR) and a box temperature (BT).
The inputs received by the TRS Controller 220 further can include data regarding certain TRS configurations and certain TRS operating modes. In one example, data regarding the first TRS configuration can be whether the TRS 120 is running on power generated by an engine (e.g., diesel engine) of a TRS generator set (genset) only, or by power generated by the engine of the TRS genset and power from an electric power source (e.g., shore power). Data regarding the second TRS configuration can be whether the TRS 120 is configured with a single zone temperature zone or multiple zone temperature. In one example, multiple zone temperature units include a dual evaporator or a single evaporator. In the case where a dual evaporator is included, the two zones can be separated by a wall in the trailer refrigerated with a single motor or dual motors.
Data regarding the first TRS operating mode can be whether the TRS is in cool mode, heat mode or defrost mode. Data regarding the second TRS operating mode can be whether the TRS is in electric mode or engine mode.
In some instances, the TRS is architecturally constructed to run on power generated by an engine (e.g., diesel engine) of a TRS generator set (genset) only, and/or power from an electric power source (e.g., shore power). In this instance, the TRS controller 220 receives input regarding the first TRS configuration. In some other instances, the TRS is architecturally constructed to run on power generated by an engine (e.g., diesel engine) of a TRS generator set (genset) only or power from an electric power source (e.g., shore power) only. In this instance, the TRS controller 220 receives input regarding the second TRS operating mode.
Details of the command signals for the desired state of the condenser fans 144a, 144b and the evaporator fan 147 will now be described. The command signals for the desired state of the condenser fans 144a, 144b can include “on state”, “off state”, “high speed state”, “low speed state” and “continuously varying speed state”. In some examples, the “on state” and “off state” command signals are employed where a single speed fan is used for each of the condenser fans 144a, 144b, “high speed state” and “low speed state” command signals are employed where a two speed fan is used for each of the condenser fans 144a, 144b, and “continuously varying speed state” commands are employed where a multi-speed fan is used for each of the condenser fans 144a, 144b.
The command signals for the desired state of the evaporator fan(s) 147 can likewise include “on state”, “off state”, “high speed state”, “low speed state” and “continuously varying speed state”. In some examples, the “on state” and “off state” command signals are employed where a single speed fan is used for the evaporator fan(s) 147, “high speed state” and “low speed state” command signals are employed where a two speed fan is used for the evaporator fan(s) 147 and “continuously varying speed state” command is employed where a multi-speed fan is used for the evaporator fan(s) 147.
Details of the various algorithms that can be stored in the memory will now be provided below.
Generally, the TRS Controller 220 is configured to implement the disclosed process of controlling the operation of the condenser fans 144a, 144b and the evaporator fan 147 as illustrated in
In some examples, the methods described herein involve determining one or more parameters and controlling a rate of heat rejection and/or a rate of heat absorption in the TRS 120 based on the determined parameters.
In some examples, the one or more parameters may be indicative of the status of the engine 208 and/or the status of the compressor 183. The status can include, for example, health, speed and/or vitals. The health can include power capacity such as residual power capacity, lubrication status, oil status, etc. The speed can be measured, for example, in units based on rpm. The vitals can include, for example, engine pressure, cooling temperature, available horse power, etc. The status of the engine 208 and/or the status of the compressor 183 can indicate, for example, normal operation, damage etc.
In some examples, the methods can generally involve determining an engine status, determining a compressor status, and then controlling a rate of heat rejection and/or a rate of heat absorption in the TRS 120 based on the determined statuses. In some examples, controlling the rate of heat rejection can involve controlling the condenser fans 144a, 144b. In some examples, controlling the rate of heat absorption can involve controlling the evaporator fan 147. In general, controlling the condenser fans 144a, 144b and/or the evaporator fan 147 lead to optimal temperature control of the TRS 120.
In some examples, the methods involves determining at least one parameter that is indicative of a status of the engine 208 and/or at least one parameter that is indicative of a status of the compressor 183 and controlling a rate of heat rejection and/or a rate of heat absorption of the TRS 120 based on the determined parameters.
At 308, the TRS Controller 220 determines a discharge pressure temperature saturation (DPTSAT), a minimum pressure temperature saturation (MPTSAT), a minimum discharge pressure (DPMIN), an ambient temperature (AT); an engine coolant temperature (ECT), an engine intercooler temperature (EICT), an engine cooling fan request (ECFR), an engine intercooler fan request (EIFR) and a box temperature (BT) using the plurality of sensors 222.
In some examples, the TRS Controller 220 also determines the configuration of the TRS 120 and/or the operating mode of the TRS 120 (not shown). As described above, the TRS Controller 220 can receive as input data regarding certain TRS configurations of the TRS 120 and/or certain TRS operating modes of the TRS 120.
At 312, the TRS Controller 220 determines whether there is a conflict between the DPTSAT, the MPTSAT, the DPMIN, the AT, the ECT, the EICT, the ECFR, the EIFR, the MOTI and the box temperature and predetermined operating conditions. Generally, the predetermined operating conditions prioritizes (1) prevention of damage to the power source 208, (2) cooling of the internal space 150, and (3) saving energy, in that order. In one example, a conflict occurs when the MOTI and the MPTSAT are incompatible. In this instance, the MOTI takes priority over MPTSAT. If there is a conflict, then the condenser fans 144a, 144b and the evaporator fan 147 operate based on the predetermined operating conditions at 322.
If there is no conflict, then the condenser fans 144a, 144b are turned on or off depending on certain conditions {circle around (1)} (details of the conditions {circle around (1)} are illustrated in
Details of the conditions {circle around (1)} will now be described with reference to
If T1 is not greater than or equal to X1 at 331, then the TRS Controller 220 determines if T1 is greater than or equal to a second predetermined value (X2) at 345. In one example, X2 can be about 15° F. If T1 is greater than or equal to X2 at 345, then the condenser fan 144b is turned on at 348. The process then proceeds to 341, where the condenser fan 144b is turned on for a predetermined time period.
If T1 is not greater than or equal to X2 at 345, then the TRS Controller 220 determines if the ECT is greater than or equal to a third predetermined value (X3) at 354. In one example, X3 can be about 200° F. If ECT is greater than or equal to X3 at 354, then the condenser fan 144a and/or the condenser fan 144b is(are) turned on at 362. The process then proceeds to 341, where the condenser fans 144a, 144b are turned on for a predetermined time period.
If the ECT is not greater than or equal to X3 at 354, then the TRS Controller 220 determines if the ECT is less than or equal to a fourth predetermined value (X4) at 365. In one example, X4 can be about 165° F. If the ECT is not less than or equal to X4 at 365, then the algorithm proceeds back to 308.
If the ECT is less than or equal to X4 at 365, then the TRS Controller 220 determines if T1 is less than a fifth predetermined value (X5) at 372. In one example, X5 can be about 1° F. If T1 is less than or equal to X5 at 372, then the condenser fan 144a is turned off at 378. The process then proceeds to 341, where the condenser fan 144a is turned off for a predetermined time period.
If T1 is not less than or equal to X5 at 372, then the TRS Controller 220 determines if T1 is less than a sixth predetermined value (X6) at 384. In one example, X6 can be about 3° F. If T1 is less than X6 at 384, then the condenser fan 144b is turned off at 395. The process then proceeds to 341, where the condenser fan 144b is turned off for a predetermined time period.
Details of the conditions {circle around (2)} will now be described with reference to
If T2 is not greater than or equal to X7, then the TRS Controller 220 determines if T2 is less than an eighth predetermined value (X8) at 410. In one example, X8 can be about 6° F. If T2 is not less than or equal to X8 at 410, then the evaporator fan 137 is operated at high speed at 408. The process 300 then proceeds to 409, where the evaporator fan 137 is operated at high speed for a predetermined time period, and then goes back to 308. If T2 is less than or equal to X8 at 410, then the evaporator fan 137 is operated at low speed at 412. The process 300 then proceeds to 409, where the evaporator fan 137 is operated at low speed for a predetermined time period, and then goes back to 308.
Note that in the above example illustrated in
In some examples, the condenser fans 144a, 144b and the evaporator fan 147 can run on induction motors. In this instance, the condenser motor ON and OFF states are controlled to minimize the power used to move air through the condenser/radiator coils. The evaporator motor speed is controlled to optimize the power used to move air through the evaporator coil. The control algorithm can establish a balance between minimum power and sufficient air flow for temperature control purposes.
In some examples, the condenser fans 144a, 144b and the evaporator fan 147 can run on electronically commutated motors. In this instance, the condenser motor speed is controlled to minimize the power used to move air through the condenser/radiator coils. The evaporator motor speed is controlled to optimize the power used to move air through the evaporator coil. The control algorithm can establish a balance between minimum power and sufficient air flow for temperature control purposes.
In some embodiments, the TRS Controller 220 is further configured to provide controller instructions to drive single contactors at points 1-6 shown in
At 462, the TRS Controller 220 determines the operating mode of the TRS 120. As discussed above, the inputs of the TRS Controller can include data regarding certain TRS operating modes. Data regarding the TRS operating mode can be whether the TRS is in a shore power mode or a genset power mode.
If the operating mode is determined to be the genset power mode, then contacts at points 1 and 2 are opened and the contacts of any combination of points 3, 4, 5 and 6 are closed at 492 so that airflow with refrigeration can be supplied to the internal space 150.
If the operating mode is determined to be the shore power mode, then a determination is made at 502 if airflow with refrigeration is to be supplied to the internal space 150. If airflow with refrigeration is to be supplied to the internal space 150, then contacts at points 1 and 2 are closed at 508.
If airflow without refrigeration is to be supplied to the internal space 150, then contact at point 1 is opened and the contact at point 2 is closed at 515.
In some other examples, the algorithm can drive multiple contacts in place of single contacts, for example, at points 3, 4 and 5. Multiple contacts can allow multiple motor speeds when, for example, an induction motor is used.
In some other examples, the algorithm can drive continuously variable speed motors by replacing contactor switching commands with Pulse Width Modulation or other types of variable control signals from the algorithm through the controller outputs.
In yet some other examples, the fan control algorithm can drive commands for condenser fan 144b using only refrigeration heat rejection requirements as input and/or engine intercooler and refrigeration heat rejection requirements as input.
In yet some other examples, the fan control algorithm can drive commands for condenser fan 144a using only refrigeration heat rejection requirements as input and/or engine cooling and refrigeration heat rejection requirements as input.
The following Table I provides examples of operation conditions at different condenser fan speeds and evaporator fan speeds.
Any one of aspects 1-14 can be combined with one another. Any one of aspects 15-20 can be combined with one another. Any one of aspects 1-14 can be combined with any one of aspects 15-20.
Aspect 1. A system, comprising:
a compressor;
an engine;
one or more sensors configured to detect at least one parameter that is indicative of a status of an engine and/or at least one parameter that is indicative of a status of a compressor, and
a controller that is configured to
(c1) if T1 is greater than a first predetermined value, then operate the first condenser fan in the first state, wherein T1 is the difference between the DPTSAT and the AT determined (a);
With regard to the foregoing description, it is to be understood that changes may be made in detail, especially in matters of the construction materials employed and the shape, size and arrangement of the parts without departing from the scope of the present invention. It is intended that the specification and depicted embodiment to be considered exemplary only, with a true scope and spirit of the invention being indicated by the broad meaning of the claims.
Filing Document | Filing Date | Country | Kind |
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PCT/US2013/078015 | 12/27/2013 | WO | 00 |
Number | Date | Country | |
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61746656 | Dec 2012 | US |