Patent Application
20140000299
The present invention is related to air conditioners for use with refuge shelters in hazardous environments, such as a mine. As used herein, references to the “present invention” or “invention” relate to exemplary embodiments and not necessarily to every embodiment encompassed by the appended claims.) More specifically, the present invention is related to air conditioners for use with refuge shelters in hazardous environments, such as a mine, where a compressor and a condenser of the air conditioner is located outside of the refuge shelter and an evaporator of the air conditioner is located in the refuge shelter and connected to the compressor and the condenser.
This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the present invention. The following discussion is intended to provide information to facilitate a better understanding of the present invention. Accordingly, it should be understood that statements in the following discussion are to be read in this light, and not as admissions of prior art.
In emergency situations where the environment becomes hazardous to people, a refuge shelter provides a safe protected environment from the outside hazardous environment. Over time, if people must stay in the refuge shelter, steps must be taken to maintain the environment inside the refuge shelter as safe, such as maintain the carbon dioxide level or the temperature in locations where heat is an issue and the temperature cannot be maintain at safe comfortable levels because the outside environment is too warm to cool the refuge shelter. Furthermore, in certain environments, such as in coal mines, there is risk of explosion that must be avoided. Consequently, there is a need for an air conditioner for a refuge shelter that is safe to use in a mine which will avoid the possibility of causing an explosion.
The present invention pertains to an air-conditioning system for a mine that operates in a mine environment. The system comprises a rigid container having a door, which when open defines an opening. The system comprises a passive condenser disposed in the container alongside the door so when the door is open, the condenser is exposed to the mine environment. The system comprises an explosion proof enclosure disposed in the container. The system comprises a first fluid pump which pumps fluid disposed in the enclosure. The system comprises a portable evaporator disposed in the container. The system comprises a compressor which pumps refrigerant. The system comprises a controller in communication with the evaporator which controls the evaporator operation. The system comprises a battery array disposed in the container and electrically connected to the first fluid pump. The system comprises a condenser.
The present invention pertains to a condenser. The condenser comprises a housing. The condenser comprises a bottom portion having a refrigerant coils through which refrigerant flows and bottom fins which contact the refrigerant coils and which cool the refrigerant passing through the coils. The condenser comprises a chimney portion disposed above the bottom portion that draws air into the bottom portion and channels the air up through the chimney portion.
The present invention pertains to a refuge system for protecting users from a toxic environment. The system comprises a refuge shelter. The system comprises an air conditioner in communication with the shelter. The air conditioner having an evaporator disposed in the shelter and a shell disposed outside and apart from the shelter. The shell having a condenser and a compressor. The compressor pumping refrigerant to the condenser and the evaporator through hoses that connect the compressor and the condenser and the evaporator together in a fluidic loop.
The present invention pertains to an evaporator. The evaporator comprises a housing having fins and refrigerant coils in fluidic communication with the fins through which refrigerant flows, there being 4-8 fins per inch.
The present invention pertains to a method for cooling a refuge shelter. The method comprises the steps of connecting refrigerant hoses attached to a compressor and a condenser in a shell to an evaporator in the shelter. The shell disposes outside and apart from the shelter. There is the step of activating the compressor which pumps refrigerant to the evaporator and the condenser.
The present invention pertains to an inflatable chamber having an airlock, the airlock includes a tube that extends from the chamber's outer surface into the chamber's interior, the tube having an outer end attached to the outer surface and an inner end, an outer closure that closes the outer end and an inner closure that closes the inner end.
The present invention pertains to a container in an environment. The container comprises an explosion proof enclosure isolated from the environment. The container comprises a purge system in communication with the enclosure.
The present invention pertains to an electricity source. The source comprises a battery having a plate and a case. The source comprises a terminal formed of a cable which extends out of the case and is welded to the plate.
In the accompanying drawings, the preferred embodiment of the invention and preferred methods of practicing the invention are illustrated in which:
a-27d show top, side, front and back views, respectively, of the condenser.
Referring now to the drawings wherein like reference numerals refer to similar or identical parts throughout the several views, and more specifically to
The condenser 26 may be mounted to the door 28 so an opening at the bottom of the housing 146 is disposed at least 1 inch above the ground to allow air to flow through the opening and to the bottom portion 148 of the condenser 26. The condenser 26 may have a chimney portion 150 having upper fins 156 that guide air flow through them out of the chimney portion 150 and prevents turbulent flow of the air through the condenser 26, as shown in
The present invention pertains to a condenser 26. The condenser 26 comprises a housing 15. The condenser 26 comprises a bottom portion 148 having refrigerant coils 152 through which refrigerant flows and bottom fins 154 which contact the refrigerant coils 152 and which cool the refrigerant passing through the coils 152. The condenser 26 comprises a chimney portion 150 disposed above the bottom portion 148 that draws air into the bottom portion 148 and channels the air up through the chimney portion 150.
The present invention pertains to a refuge system 15 for protecting users from a toxic environment, as shown in
The shelter 12 may have a container 84 and an inflatable tent 82 or chamber that when inflated defines a protected environment for the users and in which the evaporator 18 is disposed. The container 84 having pressurized gas tanks that release breathable air or oxygen into the environment and maintains positive pressure in the inflated tent 82 relative to an atmosphere outside the tent 82.
The present invention pertains to an evaporator 18, as shown in
The present invention pertains to a method for cooling a refuge shelter 12. The method comprises the steps of connecting refrigerant hoses 42, 44 attached to a compressor 38 and a condenser 26 in a shell 24 to an evaporator 18 in the shelter. The shell 24 disposes outside and apart from the shelter. There is the step of activating the compressor 38 which pumps refrigerant to the evaporator 18 and the condenser 26.
The present invention pertains to an inflatable chamber 82 having an airlock 72, as shown in FIGS. 2 and 11-13. The airlock includes a tube 83 that extends from the chamber's outer surface into the chamber's interior. The tube 83 having an outer end 85 attached to the outer surface and an inner end 87, an outer closure that closes the outer end and an inner closure that closes the inner end.
The outer closure may include an outer drawstring 80 that when pulled closes the outer end and the inner closure includes a zipper 76 at the inner end to open and close the inner end, and an inner drawstring 80 that when pulled closes the inner end.
The present invention pertains to a container in an environment. The container comprises an explosion proof enclosure 22 isolated from the environment. The container comprises a purge system 30 in communication with the enclosure 22.
The present invention pertains to an electricity source. The source comprises a battery 19 having a plate 35 and a case 36. The source comprises a terminal 32 formed of a cable 34 which extends out of the case 36 and is welded to the plate 35.
In the operation of the invention, the MSHA Approved 96 hour, 24 VDC Air Conditioning System 10, as shown in
The structural shell 24 of the system 10 is designed to meet the MSHA CFR 30, Part 7 design requirements for Refuge Shelters 12 which require the structure to withstand a 200 millisecond, 15 PSI blast. In order to meet that requirement, this system 10 has a housing of a shell 24 of a Strata Worldwide LLC M10 refuge chamber currently in production. This shell 24 will be modified slightly to house the components of the air conditioning system 10. These modifications include installation of an air tight bulkhead 14 to separate the components designed to be isolated from the mine atmosphere and those components designed to be exposed to the mine atmosphere or those components which will be taken into the Refuge Shelter 12. The shell 24 will also be modified to accommodate a sled to contain the batteries 21 and explosion proof (XP) enclosure 22, the door 28 mounted condenser 26 as well as control and display panels necessary for system 10 operation.
One of the difficulties in obtaining approval for a system such as this is that the CFR 30, Part 7 regulations require that equipment located “inside” the refuge alternative must be IS (Intrinsically Safe) or permissible while electrical equipment exposed to the mine environment must be IS. The previous interpretation of this regulation rendered design of an air conditioning system 10 virtually impossible due to the level of energy required to remove the heat generated in an occupied refuge shelter or alternative. However, it has been determined that MSHA is of the opinion that the law also allows for permissible equipment if the equipment is isolated from the mine environment. It is that interpretation which has allowed the development of a permissible system due to a unique technique of isolating the system from the mine environment.
The isolation system employed by the MSHA Air Conditioning System 10 uses two means of isolation. First, the components are housed in a gasketed steel structure, previously referred to as the shell 24. This structure is vacuum tested to insure the integrity of the seals, welds, and panels after fabrication. The second means of isolating the components from the mine atmosphere is a purge system 30 that releases nitrogen into the XP enclosure 22 creating a positive pressure environment in the control and power section, compartment 92, thus forcing out any possible contaminants from the mine atmosphere and preventing any ingress of methane. See
Although MSHA has determined that the system enclosed in the isolated atmosphere must be permissible, there are a number of unique designs in the system in order to meet the permissible criteria.
First, the battery system 20 must meet a special design as outlined in CFR 30, Part 7 which discusses the battery 21 restraint system, required venting, connection systems, etc. The system is designed to meet these criteria. One of the unique aspects of the battery 21 connection system is a special battery 21 designed specifically for this application where the battery 21 terminal 32 is a battery cable 34 that is internally welded to the battery 21 plate that then extends approximately 8″ out of the battery case 36. See
Second, the permissible design requires that all components such as motors, relays, switches, pumps, etc. must be housed within an MSHA approved XP enclosure 22. This enclosure 22 is designed to contain an explosion in the event that explosive gas made its way into the enclosure 22 and was ignited by a spark from a motor, etc. This then creates challenges to move power, fluids, gases, etc. from this XP enclosure 22, necessary for cooling and control, to the Refuge Shelter 12. MSHA rules require that all components exposed to the mine atmosphere be IS. For an air conditioning system 10 to function, it is necessary to remove latent and sensible heat (temperature and humidity) given off by the occupants of the Refuge Shelter 12 and that energy must be expelled into the mine environment. This is accomplished by the evaporation and compression of refrigerant which is circulated from an evaporator 18 located in the refuge back to the compressor 38 and condenser 26 located in the shell 24 via hoses. Moving the refrigerant out of the XP enclosure 22 required the design of a flame arrestor 40 which would both freely pass the refrigerant but would also contain any possible explosion emanating from the XP enclosure 22. This flame arrestor 40, as shown in
Finally, due to the IS requirements, the control system used to operate the air conditioning system 10 from within the chamber is a fiber optic design. This control system is designed to allow the miners to start and stop as well as monitor and reset the system from within the refuge. See
This air conditioning system 10 operates in many ways like a conventional air conditioner. However, the operating environment requires unique features, many of which have already been described. Some additional unique controls include:
Inside the XP enclosure 22, as shown in
The overall operation of the cycling of the refrigerant through the evaporator 18 and the condenser 26 with the reservoir 46 by the compressor 38 is essentially a standard air-conditioning unit. However, because of the danger of explosion inside a mine, extra care has been taken to respect this dangerous environment and has resulted in the condenser 26 being completely passive in regard to the air cooling the refrigerant as it flows through the condenser 26. The compressor 38 is inside the XP enclosure 22 because it requires electricity so if there is a spark or some potential fire, the XP enclosure 22 contains the damage explosion or fire can cause. Furthermore, remotely located from the compressor 38 and condenser 26 is the evaporator 18 which is located inside the refuge chamber where the miners reside for the cooling of the air.
All cables or wiring that extends from the inside of the XP enclosure 22 to outside the XP enclosure 22 pass through MSHA approved glands 56. Media flowing through hoses such as the refrigerant, compressed air or atmospheric gasses flowing to or from the XP enclosure 22, pass through flame arrestors 40. The flame arrestors 40 dissipate essentially all of flames associated with an explosion or fire inside the XP enclosure 22 so by the time any gas from the fire or explosion exits the flame arrestor 40, the gas has cooled to a temperature below that which would ignite any methane in the surrounding environment of the mine.
The flame arrestor 40, as shown in
Each hose, such as the supply and return hose, passes through the XP enclosure 22 in two parts. The first part, inside the XP enclosure 22, extends from its component source, such as the compressor 38, to the portion of a flame arrestor 40 extending into the XP enclosure 22. The second part, outside the XP enclosure 22, attaches to and extends from the portion of the flame arrestor 40 extending out from the XP enclosure 22, to the ultimate destination, for instance, the evaporator 18. In this way, the fluid in any given hoses safely passes through a wall 112 of the XP enclosure 22. For cabling, such as the optical fiber, MSHA approved glands 56, which are well known in the art, are used to allow the cabling or optical fiber to safely extend through the wall 112 of the XP enclosure 22 with essentially no risk of explosion or fire escaping through the aperture that has the cabling or fiber.
The first and second electric powered air pumps 58, 60 disposed inside the XP enclosure 22, connect to an air supply hose 62 that extends and connects to the evaporator 18, and an air return hose 64 that extends from the evaporator 18 to the air pumps 58, 60. The air pumps 58, 60 are in parallel so they provide a redundancy in the pumping of air, and provide increased pressure and volume to the air that is pumped. The air supply hose 62 and the air return hose 64 form a closed loop so the air inside the closed loop constantly circulates around and around never escaping. This air turns a fan motor 66, such as model Lynx Pro 3 hand piece manufactured by MTI Dentalin, in communication with the loop. The fan motor 66 has a shaft 68 that extends from the fan motor 66 and has a fan 70 at its outer end that is disposed in a fan housing 71. As the air in the loop moves through the loop, it turns the air motor, but cannot escape. As the air motor turns, so does the shaft 68, which in turn rotates the fan 70, which forces air in the Refuge Shelter 12 to pass through the evaporator 18. The air supply hose 62 and the air return hose 64 have self-closing fittings as is well known in the art, so that when the ends of either of the air houses are not connected, but open, the ends automatically close so no air inside the hoses can escape. In this way, the air present during their manufacture becomes trapped inside the hoses and is all that is necessary to be used to circulate through the air loop and power the air motor to turn the fan 70. The closed loop is an important design feature in that it prevents introduce contaminants into the refuge chamber.
The supply and return hoses for the refrigerant and the air, and the control cable 74 from the XP enclosure 22 pass into the refuge chamber through what can be considered a mini airlock 72 in the tent 82, as shown in
The air conditioning system 10 uses a different type of condenser 26, known as a passive condenser 26, to achieve energy efficient heat rejection. See
The condenser 26, because it is passive, is much larger than it otherwise would be if there was air forced about the condenser 26 to cool the refrigerant passing through the condenser 26. However, because of the danger of an explosion in a mine, by being a passively operated condenser 26, any risk or threat of explosion from the operation of the condenser 26 is eliminated. The condenser 26 is positioned at the end of the steel shell 24. The end of the shell 24 alongside the condenser 26 has a large door 28 which opens up to the mine environment so the atmosphere of the mine can contribute to the cooling of the refrigerant passing through the condenser 26.
The anatomy of the passive condenser 26 has some fundamental differences than traditional condensers. First, the passive condenser 26 uses a flue that enhances the natural airflow through the coils 152 by the principles of buoyancy; hot air rises through the flue, pulling cooler air into the intake of the condenser 26. The flue essentially acts as a duct that forces the hot air to rise through it similar to that of a chimney in a house. Without the flue, the natural air flow at the outlet of the condenser 26 becomes turbulent, disrupting the air flow while reducing the condenser's thermal capacity. This flue is part of the condenser 26 structure, and is not removable. The condenser 26 is bolted to the door 28 of the shell 24. When the door 28 of the shell 24 is opened, the condenser 26 is moved into the environment of the mine and is exposed to the air in the mine. The intake of the condenser should be at least about 3 inches above ground.
Second, the “wetted” portion of the coil, which houses the refrigerant coils 152, is located in the bottom portion 148 of the condenser 26, heating the incoming air, and causing the air to rise through the chimney portion 150. An important characteristic of this portion of the condenser 26 is the fin spacing. Most condensers utilize about 12-14 fins per inch, which is well suited for forced convection condensers. However, the passive condenser 26 has only 4-8 and preferably 6 fins 154 per inch to reduce airflow restriction, which is important due to the passive condenser 26 relying on natural air flow for its heat rejection. This fin 154 spacing is considered quite “open” by industry, and is not typical of standard condensers.
Third, the chimney portion 150 of the condenser 26 has removable fins 156 that provide adjustability to maximize the condenser's performance. These fins 156 are held in place by sheet metal screws 158 that can be easily removed; after screw removal the fin 156 can slide out of the top of the condenser 26. The utility of this design is that it provides the option to adjust the condenser's performance by removing fins 156. Each fin 156 segregates the chimney's flow area into smaller chimneys, which help reduce eddy currents near the outlet of the chimney portion 150. However, with the addition of each fin 156, there is more flow restriction in the chimney portion 150. Having the capability to remove fins 156 provides the adjustability needed to find the correct balance of flow restriction vs. eddy current reduction for each mine environment the system will be placed into.
The condenser 26 may be rectangular. The fins 156 are essential flat sheets of metal. The removable fins 156 also have a flange 160 at the top that extends from the flat sheet through which the screw 158 extends to hold the sheet in place.
The evaporator 18, as shown in
In regard to clogging, when an air conditioner is operated in a high moisture environment such as is the condition in a refuge chamber, water droplets accumulate on the fins as the air is cooled. If the fin spacing is too close, the surface tension of the water causes the water droplets to cling to the fins and accumulate to such a degree that the entire evaporator 18 is completely filled with water and prevents air from flowing through the evaporator 18. By spreading the fins apart, while the “dry air” efficiency of the energy transfer is reduced, the force of gravity overcomes the natural surface tension of water and the water flows out of the evaporator 18. This water shedding process is improved via the use of the hydrophilic coating which inhibits adhesion of water to the fins.
The shell 24 has a bulkhead 14 that defines a compartment 92 that houses the condenser 26 and the evaporator 18, as shown in
Inside the XP enclosure 22 is a battery charger 86 that is used to charge the batteries 21 during maintenance. The battery charger 86 has an electrical interface that connects to the electrical power supply present in the mine to receive electricity from the mine's power supply to recharge the batteries 21.
The battery charger 86 is connected to the batteries 21 by way of a bank of fuses 88 and a master breaker. The batteries 21 are formed into pods 90, with four batteries 21 to a pod 90. As shown in
The battery charger 86 is connected to the master breaker and through the bank of fuses and the cables extending from the bank of fuses 88 to each pod 90. When the maintenance mode is activated, electricity flows from the mine electrical system, through the charger, master breaker and bank of fuses 88 to the cables and ultimately to each battery 21 in each pod 90 to charge each battery 21. A failed fuse is indicated by an LED readout on the status panel 104, as shown in
The air pumps 58, 60 and the compressor 38, shown in
Extending from each fuse of the bank of fuses 88 is an MSHA approved cable that connects to each battery 21 in a pod 90. This electrical cable electrically connects to specially designed terminals that extend from each battery 21. See
In regard to the charging and battery system 20, since this is a battery 21 operated system, this system requires a charging system. This is accomplished by the connection of 120 VAC mine power as required (estimated to be on a 3-month interval) to replenish the battery 21 loss due to system monitoring and natural battery 21 discharge rates. Although this system uses AGM gel cell batteries 21 which greatly reduce the incidence of hydrogen off gassing during the charging cycle, the system is monitored by a (5-year rated life) hydrogen sensor 98 that disables the system in the event that hydrogen is sensed. See
In regard to the auto resetting system, the system is equipped with thermal auto-reset breakers in order to provide a high certainty of operation in a life-dependent environment.
In regard to the monitoring system, in addition to Hydrogen monitoring, this system monitors battery 21 charge level and functionality as well as charging cycles (date and duration of charge cycle), nitrogen pressure with a nitrogen pressure sensor 94, as well as operational faults. Additionally, this data is recorded by a data logger that may be retrieved via USB port at service intervals to system service system or mine central data system.
In regard to the operational modes, the system has 3 modes of operation, Standby-ready for operation, Service-for charging and data collection and Run-providing cooling for refuge alternative. See
In regard to the remote control 102, see
The refrigerant mass flow rate will fluctuate between 60 and 160 lbs./hr. This fluctuation is due to the compressor's ability to vary its speed based on the system's heat load. The air to turn the fan 70 is a fixed value, regardless of the number of occupants in the Refuge Shelter 12. The air pumps that drive the fan 70 deliver a combined total of 80 to 110 liters per minute of air, depending on atmospheric conditions. This is a closed loop system, and none of this air is intermixed with the refuge air; it is an isolated system and non-adjustable. The condenser 26 is a fixed size, and does not vary based on the number of occupants in the refuge. The evaporator 18 fan 70 will have a speed range of 1200-1800 rpm. The condenser 26 size can vary +/−2″ in each direction. The intake of the condenser 26 should be at least 3″ from the ground, which is guaranteed by where it is mounted to the door 28. The condenser 26 is bolted to the door 28 that opens.
Maintenance Schedule and Protocol
Selector Switch Modes
Testing Schedule/Configuration
Testing Schedule/Configuration (Continued)
Although the invention has been described in detail in the foregoing embodiments for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be described by the following claims.
This is a non-provisional of U.S. provisional application Ser. No. 61/690,565 filed Jun. 28, 2012.
| Number | Date | Country | |
|---|---|---|---|
| 61690565 | Jun 2012 | US |
