Patent Publication Number: US-2023158863-A1

Title: Isolated evaporator coil for a transport climate control system

Description:
FIELD 
     The embodiments disclosed herein relate substantially to a transport climate control system (TCCS). More particularly, the embodiments relate to isolating or insulating leaks from an evaporator coil of a climate control circuit for use in a TCCS. 
     BACKGROUND 
     A transport climate control system is generally used to control environmental condition(s) (e.g., temperature, humidity, air quality, and the like) within a climate controlled space of a transport unit (e.g., a truck, trailer, a container (such as a container on a flat car, an intermodal container, etc.), a box car, a semi-tractor, a bus, or other similar transport unit). The transport climate control system can include, for example, a transport refrigeration system (TRS) and/or a heating, ventilation and air conditioning (HVAC) system. The TRS can control environmental condition(s) within the climate controlled space to maintain cargo (e.g., produce, frozen foods, pharmaceuticals, etc.). The HVAC system can control environmental conditions(s) within the climate controlled space to provide passenger comfort for passengers travelling in the transport unit. In some transport units, the transport climate control system can be installed externally (e.g., on a rooftop of the transport unit, under the transport unit or on a front wall of the transport unit, etc.). 
     The transport climate control system can include a climate control circuit with a compressor, a condenser, an expansion valve, and an evaporator. A working fluid can include a refrigerant that can be compressed and expanded as it flows through the climate control circuit and can be used to heat and/or cool the particular space. 
     SUMMARY 
     The embodiments described herein are directed to isolating or insulating at least portions of an evaporator coil within a climate control unit (CCU) of a TCCS so as to reduce or even eliminate adverse effects caused by a leaked working fluid (e.g., leaked refrigerant). Such adverse effects may include a threat of ignition, asphyxiation of occupants, damage to cargo, and other harmful effects caused by emission of a noxious gas. 
     The embodiments described, recited, and suggested herein facilitate understanding of an evaporator coil within a CCU, which may include brazed points that are vulnerable to leakage of a refrigerant flowing therein. 
     In accordance with at least one embodiment, a climate-control unit (CCU) of a transport unit is provided. The CCU includes a condenser unit, an evaporator unit, and a leak isolation structure. The evaporator unit includes an evaporator coil. The evaporator coil includes a plurality of evaporator tubes and a plurality of turns. The evaporator coil traverses at least a portion of an interior of the evaporator unit. The leak isolation structure is configured to insulate at least one of the plurality of evaporator tubes from a leak at one of the plurality of turns of working fluid passing through the evaporator coil. 
     In some embodiments, the leak isolation structure is a detachable cap. The plurality of turns is disposed within the detachable cap. In some embodiments, a head plate with a turn side and a tube side is provided such that the plurality of turns is disposed on the turn side and the plurality of evaporator tubes are disposed on the tube side. In some embodiments, the detachable cap is attachable and sealed to the head plate such that the plurality of turns disposed within the detachable cap are isolated from the plurality of evaporator tubes. In some embodiments, the detachable cap is attached to the head plate with a pressure resistant sealant. In some embodiments, the detachable cap is configured to vent any leaked working fluid to atmosphere via a duct. In some embodiments, the detachable cap is comprised of sheet metal or plastic. 
     In some embodiments, the leak isolation structure is a sealed bulkhead that separates the condenser unit from the evaporator unit. The sealed bulkhead includes a condenser side and an evaporator side, and the plurality of turns is disposed on the condenser side and the plurality of evaporator tubes are disposed on the evaporator side. In some embodiments, the sealed bulkhead isolates the evaporator unit from a gas escaping from the evaporator coil on the condenser unit side of the bulkhead. In some embodiments, a head plate is provided with a turn side and a tube side such that the plurality of turns is disposed on the turn side and the plurality of evaporator tubes are disposed on the tube side. The sealed bulkhead surrounds and is sealed to a perimeter edge of the head plate such that the plurality of turns are isolated from the plurality of evaporator tubes. In some embodiments, the sealed bulkhead is attached to the head plate with a pressure resistant sealant. In some embodiments, a second head plate is provided with a second turn side and a second tube side. The plurality of evaporator tubes includes a first end and a second end with the plurality of turns provided at the first end. The evaporator coil includes a plurality of second turns provided at the second end. The plurality of second turns is disposed on the second turn side and the plurality of evaporator tubes are disposed on the second tube side. The sealed bulkhead surrounds and is sealed to a perimeter edge of the second head plate such that the plurality of second turns are isolated from the plurality of second evaporator tubes. 
     In some embodiments, the leak isolation structure is a sealed duct. The plurality of the evaporator tubes is disposed within the sealed duct and at least one of the plurality of turns is disposed outside of the sealed duct. In some embodiments, a head plate is provided with a turn side and a tube side such that the plurality of turns is disposed on the turn side and the plurality of evaporator tubes are disposed on the tube side. The sealed duct is attached to the head plate such that the plurality of evaporator tubes disposed within the sealed duct is isolated from the plurality of turns. In some embodiments, the sealed duct is attached to the head plate with a pressure resistant sealant. 
    
    
     
       DRAWINGS 
       References are made to the accompanying drawings that form a part of this disclosure and which illustrate embodiments described in this specification. Various changes and modifications will become apparent to those skilled in the art from the following detailed description. The use of the same reference numbers in different figures indicates similar or identical items. 
         FIG.  1    illustrates a transport climate control system for a transport unit that is attached to a vehicle, in accordance with at least one embodiment described and/or recited herein. 
         FIG.  2    is a schematic diagram of an embodiment of a climate control unit for a transport climate controlled system, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
         FIG.  3    illustrates a perspective view of an inner side of a bulkhead with an evaporator mounted on an inside surface of the bulkhead, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
         FIG.  4 A  illustrates an evaporator coil, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
         FIG.  4 B  illustrates another evaporator coil, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
         FIG.  5    illustrates a leak isolation structure shown as a lid-type covering for at least a portion of an evaporator coil, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
         FIG.  6    illustrates a leak isolation structure shown as a duct-type covering for at least a portion of an evaporator coil, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
         FIG.  7 A  illustrates a leak isolation structure shown as a bulkhead that is at least partially sealed relative to an evaporator coil, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
         FIG.  7 B  illustrates a leak isolation structure shown as a bulkhead that is sealed relative to opposing ends of an evaporator coil, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments disclosed and recited in this disclosure relate substantially to a transport climate control system (TCCS). More particularly, the embodiments relate to isolating or insulating leaks from an evaporator coil of a climate control circuit for use in a TCCS. 
     A CCU, in accordance with the embodiments described and recited herein, may be configured to create optimal air flow on both a condenser side, e.g., a side having condenser unit, and an evaporator side, e.g., a side having an evaporator unit. The front and rear sides may be divided by a bulkhead that provides structural support for various components of the CCU, such as an air filter, a fuel filter, an evaporator blower, condenser blowers, an evaporator coil, condenser coils, etc. The embodiments described and recited herein are directed towards isolating or insulating leaks at, e.g., critical joints, of an evaporator coil, thus eliminating the possibility of harmful refrigerants leaking into the rear side, i.e., evaporator unit, of the CCU. 
     In the following detailed description, reference is made to the accompanying drawings, which are included as a part of the description. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Furthermore, unless otherwise noted, the description of each successive drawing may reference features from one or more of the previous drawings to provide clearer context and a more substantive explanation of the current example embodiment. Still, the example embodiments described in the detailed description, drawings, and claims are not intended to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as substantially described herein and illustrated in the drawings, may be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein. 
     While the embodiments described below illustrate different embodiments of a transport climate control system, it will be appreciated that the isolated evaporated coil is not limited to the transport climate control system or a climate-control unit (CCU) of the transport climate-control system. 
     The embodiments disclosed and recited herein are directed towards insulating, isolating, and/or relocating evaporator coil joints into a space that is insulated, sealed, or repositioned into a space external to other components of the evaporator unit, a climate controlled space (e.g., cargo area), or any area that has a potential source of ignition so that any potential leak into the corresponding evaporator coil may be mitigated below a flammable concentration, away from a potential source of ignition. 
     Accordingly, the embodiments disclosed and recited herein are configured by taking into account portions of an evaporator coil that attach to different components of a climate control circuit to thereby isolate potential leak points of the evaporator coil from an evaporator space. 
     Further, in accordance with at least one embodiment, a shape of the evaporator coil may be reconfigured from a straight block to relocate the return bend end into the condenser side of a sealed bulkhead. That is, such configuration, which obviates a need for a duct, any potential leak point corresponding to the evaporator coil is isolated from other components of the evaporator unit, a climate controlled space (e.g., cargo area), or any area that has a potential source of ignition. 
     In accordance with another example embodiment, the return bend of the evaporator coil may be contained within a removable leak isolation structure (e.g., cover, cap, etc.) to isolate any potential leak joints. By this configuration, evaporator coil tubes of the evaporator may be disposed on the evaporator side of a bulkhead within the CCU, but any potential leak point, e.g., return vent and/or manifold, may be isolated, venting downward to atmosphere outside of the isolation structure, via a vent tube, hose, or duct, detachably provided for vent routing. The leak isolation structure (e.g., cover, cap, etc.) may be made of sheet metal or plastic and fits over a top of the return vents. The leak isolation structure (e.g., cover, cap, etc.) may further connect to a head plate, and may be vented to atmosphere via a hose, tube, or duct. Potential leak points may be isolated due to the absence of ignition sources within the covered area. 
     In accordance with still another example embodiment, air from the condenser side of a bulkhead within a CCU may be ducted into an isolated evaporator return bend area, thus reducing any potential buildup of refrigerant gas leaking from the evaporator coil. That is, such configuration can include an entirety of the evaporator coil being within the condenser air stream, and the evaporator coil is exposed into the evaporator side of the bulkhead within the CCU with a corresponding inlet and outlet being exposed to facilitate air exchange. 
     In accordance with at least one other example embodiment, an end of the evaporator coil may be coated with a pressure resistant sealant. 
       FIG.  1    illustrates a TCCS  20  for a climate-controlled transport unit  1  that is attached to a tractor  5 , in accordance with at least one embodiment described and/or recited herein. The climate-controlled transport unit  1  includes a transport unit  10  and the corresponding TCCS  20 . 
     The transport unit  10  may be attached to tractor  5  that is configured to tow the transport unit  10 , although transport unit  10  may alternatively be parked and detached from tractor  5 . Note that the embodiments described herein are not limited to tractor and trailer units, but may apply to any type of transport unit such as e.g., a truck, trailer, a container (such as a container on a flat car, an intermodal container, etc.), a box car, a semi-tractor, a bus, or other similar transport unit. 
     The TCCS  20  includes a climate control unit (CCU)  30  that provides environmental control, e.g., temperature, humidity, air quality, etc., within a climate-controlled space  12  of transport unit  10 . 
     The CCU  30  may provide conditioned air into the climate-controlled space  12 , i.e., internal space, of the transport unit  10  to provide a desired conditioned environment for goods within. The desired conditioned environment for the climate-controlled space  12  may have one or more desired environmental conditions, e.g., temperature, humidity, air quality, etc., of the climate-controlled space  12 . For example, the CCU  30  may provide cooled air to the climate-controlled space  12  when perishable goods are within the transport unit  10 ; additionally or alternatively, the CCU  30  may remove humidity from the air within the climate-controlled space  12  depending on needs of the goods within the transport unit  10 , e.g., when electronics are within the transport unit  10 . 
     The CCU  30  may be disposed on a front wall  14  of the transport unit  10 ; that is, on a side of the transport unit facing the forward direction as when climate-controlled transport unit  1  that is attached to a tractor  5 . In one or more alternative embodiments, the CCU  30  may be disposed, for example, on a roof  14  or another wall of the transport unit  10 . 
     The climate-controlled transport unit  1  may include at least one of a battery (not shown) or an engine (not shown) as a power source. 
     The TCCS  20  may be a hybrid power system that uses a combination of battery power and engine power or an electric power system that does not include or rely upon an engine of the TCCS  20  or the tractor  5  for power. The TCCS  20  may also include a programmable climate-controller  40  and one or more sensors  50 . The one or more sensors  50  may be configured to measure one or more parameters of the climate-controlled transport unit  1 , e.g., an ambient temperature and/or ambient humidity outside of the transport unit  10 , a compressor suction pressure, a compressor discharge pressure, a temperature of air supplied into the climate-controlled space  12  by the CCU  30 , a temperature of air returning from the climate-controlled space  12  to the CCU  30 , humidity within the climate-controlled space  154 , etc., and to communicate parameter data to the climate-controller  40 . The climate-controller  40  may be configured to control operation of the TCCS  20 , including components of the climate-control circuit. The climate-controller  40  may be a single integrated control unit  42  or a control unit formed by a distributed network of climate-controller elements  42 ,  44 . The number of distributed control elements in a given network may depend upon the particular application of the principles described herein. 
     With regard to at least programmable climate-controller  40  and one or more sensors  50 , dashed lines are shown in  FIG.  1    to illustrate features that would not otherwise be visible in the view shown. 
       FIG.  2    is a schematic diagram of an embodiment of a CCU  30  for a TCCS (e.g., the TCCS  20  shown in  FIG.  1   ), in accordance with at least one non-limiting example embodiment described and/or recited herein. 
     The CCU  30  is utilized in a transport climate control system to condition a climate-controlled space  12 . The CCU  30  includes a climate control circuit  130  that is configured and utilized to control one or more environmental conditions, e.g., temperature, humidity, air quality, etc., of the climate-controlled space  12 . The CCU  30  includes, at least, an evaporator unit  110  and a condenser unit  120 . 
     The evaporator unit  110  may include an evaporator air inlet  112 , which alternatively be referred to as an air return inlet, and an evaporator air outlet  114 . Air passes through the evaporator unit  110  by entering through the evaporator air inlet  112  and exiting through the evaporator air outlet  114 . After air from the climate-controlled space  12  enters the evaporator unit  110  through the evaporator air inlet  112 , the air is conditioned within the evaporator unit  110 , i.e., heated or cooled; and the conditioned air is discharged from the evaporator unit  110  through the evaporator air outlet  114 . In some embodiments, the evaporator unit  110  can include one or more evaporator blowers (not shown) that discharges conditioned air through the evaporator air outlet  114  and retrieves air from the climate-controlled space  12  through the evaporator air inlet  112 . The conditioned air flows from the evaporator air outlet  114  to the climate-controlled space  12  to condition the climate-controlled space  12 . 
     The condenser unit  120  may include an ambient air inlet  124  and an ambient air outlet  126 . Ambient air from the external environment  104 , e.g., ambient air from outside the climate-controlled transport unit  1 , flows through the condenser unit  120  by entering through the ambient air inlet  124  and exiting through the ambient air outlet  126 . In some embodiments, the condenser unit  120  can include one or more condenser fans (not shown) that push air out of the condenser unit  120  through the ambient air outlet  126 . 
     Evaporator unit  110  may include a damper  118  that regulates the flow rate of the conditioned air from the condenser unit  120 . It will be appreciated that the evaporator unit  110  and the condenser unit  120 , in various embodiments, may each include one or more blower(s), fan(s) and/or damper(s) to control the flow of respective air therethrough. 
     The CCU  30  may further include a bulkhead  105  that separates an internal volume  122  of the evaporator unit  110  from an internal volume  122  of the condenser unit  120 . Accordingly, air and/or leaked gaseous working fluid within the condenser unit  120  generally does not flow into the evaporator unit  110  and therefore does not flow into the conditioned space climate-controlled space  12 . 
     The climate-control circuit  130  may extend through the bulkhead  105 . Pipes, hoses, etc., of the climate-control circuit  130  extend through the bulkhead  105  to direct the working fluid between the components of climate-control unit  130  located in the evaporator unit  110  and the components of the component of the climate-control unit  130  located in the condenser unit  120 . 
       FIG.  3    illustrates a perspective view of an inner side of a bulkhead  302  with an evaporator  110  mounted on an inside surface of the bulkhead  302 , in accordance with at least one non-limiting example embodiment described and/or recited herein. 
     In accordance with at least one embodiment, evaporator unit  110  is disposed on the inner side of the bulkhead  302 , and a condenser unit (not shown in  FIG.  3   ) is disposed on the outside of the bulkhead  302 . Evaporator coil  310  receives air from the conditioned space, as blown by an evaporator blower (not shown). A warm air flow enters through the bulkhead  302  where the two-phase refrigerant absorbs heat from air. The refrigerant generally leaves the evaporator unit  110  in a heated condition and is routed back to the compressors unit  40  for recycling. Cooled air exiting the air outlet opening is directed back into the conditioned space, where it will remove heat from the cargo and maintain the cargo at the desired temperature. 
     Accordingly, the non-limiting embodiments of evaporator coil  310  described and recited herein are designed and/or configured to reduce or even eliminate the risk of leaks of refrigerant therefrom, particularly as refrigerants having flammable and/or toxic properties are utilized. 
     Evaporator coils, including those made of copper tubing, aluminum, or other alloy with hairpin turns, have multiple brazed joints, which are vulnerable to cracks and/or other forms of fissures that could leak refrigerant out of the evaporator coil and exposing areas of the CCU and/or climate controlled space to fumes that may be flammable or toxic. Thus, the non-limiting embodiments described and recited herein have potential leak points, e.g., return vents, displaced from the evaporator space and/or climate controlled space into the condenser area. 
       FIG.  4 A  illustrates an evaporator coil  310 ′, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
     With reference to  FIGS.  2 ,  3  and  4 A  evaporator  110  may include evaporator coil  310 ′ that is generally straight and made of a plurality of evaporator tubes  312 ′ (e.g., tubing of copper, aluminum, or other alloy) with a plurality of turns  315 ′ at head plate  405 . The plurality of turns  315 ′ is disposed on a turn side  406  of the head plate  405  and the plurality of evaporator tubes  312 ′ is provided on a tube side  407  of the head plate  405 . Each of the turns  315 ′ allows a working fluid (including refrigerant) from one of the plurality of evaporator tubes  312 ′ to travel to another of the plurality of evaporator tubes  312 ′. Each of the turns  315 ′ can be about 180° hairpin turns. The turns  315 ,’ which may be regarded as brazed return ends at head plate  405 , may be formed by a brazed joint, which may be vulnerable to cracks and/or other forms of fissures that could leak refrigerant out of the evaporator coil  310 ′, exposing areas of the CCU and/or climate controlled space to fumes that may be flammable or toxic. It is noted that turns  315 ′ at the opposing head plate in  FIG.  5    may be configured as a continuous hairpin radius, and may or may not be subject to a covering as shown in  FIG.  5   . The non-limiting example embodiment of evaporator coil  310 ′ will be referenced below. 
       FIG.  4 B  illustrates another evaporator coil  310 ″ that is generally curved, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
     With reference to  FIGS.  2  and  3   , evaporator  110  may include evaporator coil  310 ″ which may also be made of a plurality of evaporator tubes  312 ″ (e.g., curved copper tubing, aluminum, or other alloy with a plurality of turns  315 ″ at head plate  405 ′ The plurality of turns  315 ″ is disposed on a turn side  406  of the head plate  405  and the plurality of evaporator tubes  312 ″ is provided on a tube side  407  of the head plate  405 . Each of the turns  315 ″ allows a working fluid (including refrigerant) from one of the plurality of evaporator tubes  312 ″ to travel to another of the plurality of evaporator tubes  312 ″. Each of the hairpin turns  315 ″ can be about 180° hairpin turns. The turns  315 ″ can be formed by a brazed joint, which can be vulnerable to cracks and/or other forms of fissures that could leak refrigerant out of the evaporator coil  310 ″, exposing areas of the CCU and/or climate controlled space to fumes that may be flammable or toxic. The non-limiting example embodiment of evaporator coil  310 ″ will also be referenced below. 
       FIG.  5    illustrates a leak isolation structure shown as a lid-type covering for at least a portion of an evaporator coil, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
     Accordingly, CCU  30  ( FIG.  2   ) of transport unit  10  may include, at least, condenser unit  120 , evaporator unit  110 , and bulkhead  302  therebetween. Evaporator unit  110  may include evaporator coil  310 ′ ( FIG.  4 A ) that traverses at least a portion of an interior of condenser unit  120  and at least a portion of an interior of evaporator unit  110 . In at least some alternative embodiments, the entirety of evaporator coil  310 ′ may be contained within evaporator unit  110 . 
     As shown in  FIG.  5   , evaporator coil  310 ′ may include cover  505  to cover the turns  315 ′ and thereby insulate at least portions of evaporator unit  110 , including portions of evaporator coil  310 ′ such as the plurality of evaporator tubes  312 ′, from leaks. That is, at least one of the turns  315 ′ can be disposed within the cover  505 . Thus, whether evaporator coil  310 ′ traverses a portion of an interior of condenser unit  120 , as well as a portion of an interior of evaporator unit  110 , or whether evaporator coil  310 ′ is contained within evaporator unit  110 , cover  505  may be a detachable cap that serves to isolate at least one turn  315 ′ in evaporator coil  310 ′ by being connected to head plate  405 , which may alternatively be referenced as an end panel, in such a manner as to prevent gas, refrigerant, or air within from escaping. A pressure resistant sealant may be applied around the outer edges of each portion of evaporator coil  310 ′ that engages with a planar portion of head plate  405  to insulate the interior of evaporator unit  110  from any refrigerant that may leak from any turn  315 ′ of evaporator coil  310 ′. Lid  505  may be detachable to permit for, e.g., adjustments to an adjustment valve (not shown) or to perform a safety check on a lead. 
     In at least some alternative embodiments, cover  505  may be hermitically sealed with a pressure resistant sealant to evaporator  110  at head plate  405 . Further, cover  505  may be made of sheet metal or plastic. Further still, whether detachable or temporarily sealed, cover  505  may be configured to vent to atmosphere, via a duct, hose(s), tube(s), etc. In accordance with at least one example embodiment, cover  505  may be fitted with hose  510  and barbed fitting  515 , coupled by clamp  520 , to vent air or gas from within cover  505  to atmosphere. 
     By the example embodiment of  FIG.  5   , upon the occurrence of a working fluid leak at any of the turns  315 ′ in evaporator coil  310 ′, by isolating the leaked working fluid between head plate  405  and lid  505 , potential sources of ignition can be isolated and/or eliminated via host  510 . 
       FIG.  6    illustrates a leak isolation structure shown as a duct-type covering for at least a portion of an evaporator coil, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
     As set forth above, with regard to the description of  FIG.  5   , CCU  30  ( FIG.  2   ) of transport unit  10  may include, at least, condenser unit  120 , evaporator unit  110 , and bulkhead  302  therebetween. Evaporator unit  110  may include evaporator coil  310 ′ that traverses at least a portion of an interior of condenser unit  120  and at least a portion of an interior of evaporator unit  110 . In at least some alternative embodiments, the entirety of evaporator coil  310 ′ may be contained within evaporator unit  110 . 
     As shown in  FIG.  6   , evaporator coil  310 ′ may be substantially entirely (including the plurality of evaporator tubes  312 ′) covered by encasement or duct  605  to isolate from potential leak points of evaporator coil  310 ′ (e.g., the turns  315 ′). Thus, whether evaporator coil  310 ′ traverses a portion of an interior of condenser unit  120 , as well as a portion of an interior of evaporator unit  110 , or whether evaporator coil  310 ′ is contained within evaporator unit  110 , encasement or duct  605  may ensure that, in the event of a working fluid leak from evaporator coil  310 ′ (particularly at the turns  315 ′), there is no leakage out of the evaporator coil  310 ′ that can expose areas of the CCU and/or climate controlled space to fumes that may be flammable or toxic. 
     That is, encasement or duct  605  covering the entirety of evaporator coil  310 ′ may be entirely within the airstream of condenser unit  120  but for the brazed turns  315 ′ at head plate  405 , which may be exposed to evaporator  405  to thereby facilitate air exchange. Accordingly, at least some of the turns  315 ′ of evaporator coil  310 ′ may be configured to be external of evaporator unit  110 , although an inlet and an outlet of evaporator coil  310 ′ are exposed to evaporator unit  110 . A pressure resistant sealant may be applied around all outer edges of each portion of duct  605  to evaporator unit  110  but for the turns  315 ′ at head plate  405 , thus preventing any leaked working fluid from entering into the duct  605 . 
       FIG.  7 A  illustrates a leak isolation structure shown as a bulkhead that is at least partially sealed relative to evaporator coil  310 ″, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
     Accordingly, CCU  30  ( FIG.  2   ) of transport unit  10  may include, at least, condenser unit  120 , evaporator unit  110 , and bulkhead  302  therebetween. Evaporator unit  110  may include evaporator coil  310 ″ ( FIG.  4 B ) that traverses at least a portion of an interior of condenser unit  120  and at least a portion of an interior of evaporator unit  110 . In at least some alternative embodiments, the entirety of evaporator coil  310 ′ may be contained within evaporator unit  110 . 
     As shown in  FIG.  7 A , the shape of evaporator coil  310 ″ ( FIG.  4 B ) is no longer a straight tube, but is rather turned about 180°, or substantially thereof. The curved shape of the evaporator coil  310 ″ can relocate the turns  315 ″ on at least one end of evaporator coil  310 ″ into condenser area  120  at head plate  705 , which may be aligned with bulkhead  302 . Not only may a pressure resistant sealant be applied around the outer edges of each portion of evaporator coil  310 ″ that engages with a planar portion of head plate  405 ′ to insulate the interior of evaporator unit  110  from any refrigerant that may leak from a brazed joint end on any turns  315 ″ of evaporator coil  310 ″; but, for the same purpose, such pressure resistant sealant may also be applied at the periphery of head plate  705  that engages with bulkhead  302 . 
       FIG.  7 B  illustrates a leak isolation structure shown a bulkhead that is sealed relative to opposing ends of evaporator coil  310 ″, in accordance with at least one non-limiting example embodiment described and/or recited herein. 
     Accordingly, CCU  30  ( FIG.  2   ) of transport unit  10  may include, at least, condenser unit  120 , evaporator unit  110 , and bulkhead  302  therebetween. Evaporator unit  110  may include evaporator coil  310 ″ ( FIG.  4 B ) that traverses at least a portion of an interior of condenser unit  120  and at least a portion of an interior of evaporator unit  110 . In at least some alternative embodiments, the entirety of evaporator coil  310 ′ may be contained within evaporator unit  110 . 
     As shown in  FIG.  7 B , the shape of evaporator coil  310 ″ ( FIG.  4 B ) is no longer a straight tube, but is rather turned about 180°, or substantially thereof. The curved shape of the evaporator coil  310 ″ can relocate the turns  315 ″ on both ends of evaporator coil  310 ″ into condenser area  120  at head plate  710 , which may be aligned with bulkhead  302 . 
     Accordingly, the turns  315 ″ may be relocated or isolated into a space that is sealed or relocated to a ventilated space outside of the rest of the evaporator coil  310 ″ (e.g., the plurality of evaporator tubes  312 ″), so that any potential leak may be mitigated below the flammable concentration away from potential sources of ignition. 
     Aspects 
     It is to be appreciated that any of the following aspects may be combined: 
     Aspect 1. A climate-control unit (CCU) of a transport unit, comprising: 
     a condenser unit;   an evaporator unit that includes an evaporator coil, wherein the evaporator coil includes a plurality of evaporator tubes and a plurality of turns, and wherein the evaporator coil traverses at least a portion of an interior of the evaporator unit; and   a leak isolation structure configured to insulate at least one of the plurality of evaporator tubes from a leak at one of the plurality of turns of working fluid passing through the evaporator coil.   

     Aspect 2. The CCU of Aspect 1, wherein each of the plurality of turns allows a working fluid from one of the plurality of evaporator tubes to travel to another of the plurality of evaporator tubes. 
     Aspect 3. The CCU of either of Aspects 1 or 2, wherein the leak isolation structure is a detachable cap, and wherein the plurality of turns is disposed within the detachable cap. 
     Aspect 4. The CCU of Aspect 3, further comprising a head plate with a turn side and a tube side, wherein the plurality of turns is disposed on the turn side and the plurality of evaporator tubes are disposed on the tube side, 
     wherein the detachable cap is attachable and sealed to the head plate such that the plurality of turns disposed within the detachable cap are isolated from the plurality of evaporator tubes. 
     Aspect 5. The CCU of Aspect 4, wherein the detachable cap is attached to the head plate with a pressure resistant sealant. 
     Aspect 6. The CCU of any of Aspects 3-5, wherein the detachable cap is configured to vent any leaked working fluid to atmosphere via a duct. 
     Aspect 7. The CCU of any of Aspects 3-6, wherein the detachable cap is comprised of sheet metal or plastic. 
     Aspect 8. The CCU of either one of Aspects 1 and 2, wherein the leak isolation structure is a sealed bulkhead that separates the condenser unit from the evaporator unit, 
     wherein the sealed bulkhead includes a condenser side and an evaporator side, and   wherein the plurality of turns is disposed on the condenser side and the plurality of evaporator tubes are disposed on the evaporator side.   

     Aspect 9. The CCU of Aspect 8, wherein the sealed bulkhead isolates the evaporator unit from a gas escaping from the evaporator coil on the condenser unit side of the bulkhead. 
     Aspect 10. The CCU of either of Aspects 8 or 9, further comprising a head plate with a turn side and a tube side, wherein the plurality of turns is disposed on the turn side and the plurality of evaporator tubes are disposed on the tube side, 
     wherein the sealed bulkhead surrounds and is sealed to a perimeter edge of the head plate such that the plurality of turns are isolated from the plurality of evaporator tubes.   

     Aspect 11. The CCU of Aspect 10, wherein the sealed bulkhead is attached to the head plate with a pressure resistant sealant. 
     Aspect 12. The CCU of either of Aspect 10 or 11, further comprising a second head plate with a second turn side and a second tube side, 
     wherein the plurality of evaporator tubes includes a first end and a second end with the plurality of turns provided at the first end,   wherein the evaporator coil includes a plurality of second turns provided at the second end,   wherein the plurality of second turns is disposed on the second turn side and the plurality of evaporator tubes are disposed on the second tube side,   wherein the sealed bulkhead surrounds and is sealed to a perimeter edge of the second head plate such that the plurality of second turns are isolated from the plurality of second evaporator tubes.   

     Aspect 13. The CCU of either one of Aspects 1 and 2, wherein the leak isolation structure is a sealed duct, wherein the plurality of the evaporator tubes is disposed within the sealed duct and at least one of the plurality of turns is disposed outside of the sealed duct. 
     Aspect 14. The CCU of Aspect 13, further comprising a head plate with a turn side and a tube side, wherein the plurality of turns is disposed on the turn side and the plurality of evaporator tubes are disposed on the tube side, 
     wherein the sealed duct is attached to the head plate such that the plurality of evaporator tubes disposed within the sealed duct is isolated from the plurality of turns. 
     Aspect 15. The CCU of Aspect 14, wherein the sealed duct is attached to the head plate with a pressure resistant sealant. 
     The terminology used in this specification is intended to describe particular embodiments and is not intended to be limiting. The terms “a,” “an,” and “the,” or even the absence of such modifiers, may refer to the plural forms as well, unless clearly indicated otherwise. The terms “includes,” “including,” “comprises” and/or “comprising,” when used in this specification, indicate the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or components. 
     With regard to the preceding 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 parts, without departing from the scope of the present disclosure. The word “embodiment” as used within this specification may, but does not necessarily, refer to the same embodiment. This specification and the embodiments described are examples only. Other and further embodiments may be devised without departing from the basic scope thereof, with the true scope and spirit of the disclosure being indicated by the claims that follow.