The invention relates to a direct venting system for a free-standing, propane powered absorption refrigeration unit or refrigerator.
Free-standing, residential propane powered absorption refrigerators are often used in remote or “off-grid” areas that do not have access to electricity for running conventional refrigerators. Previously, free-standing propane refrigerators for sale and installation in Canada were required to have either (i) a direct vent system for venting the flue gases or products of combustion directly to the outdoors or (ii) a carbon monoxide alarm with safety shut-off to ensure that the appliance shuts down if the detector senses unsafe levels of carbon monoxide. Direct vent systems typically were in the form of a kit sold separately to the refrigerator that required assembly and installation by the user/owner of the refrigerator. These were not only difficult to install but were also unreliable in that they were prone to freeze-ups during the winter months and also prone to blow-outs caused by wind blowing-out the burner flame or by flue gases collapsing in the chimney snuffing out the burner causing the refrigerator to shutdown. As well, the direct vent systems were also prone to leakage, therefore flue gases and/or products of combustion were often leaked to the interior during use and therefore did not provide true venting of the system to the outdoors. Accordingly, previous direct vent systems were perceived to be unreliable and were extremely unpopular with customers. Early versions of the carbon monoxide alarm with safety shut-off tended to be extremely sensitive and therefore prone to false alarms causing the appliance to shutdown. Improvements to the carbon monoxide alarm with safety shut-off, which made them far more reliable, led to dramatic decline in the demand for direct vented appliances.
Based on perceived safety concerns, Provincial safety authorities, in conjunction with Inter-Provincial safety authorities, eventually mandated that all free-standing propane refrigerators for residential use (i.e. installed in a primary dwelling) be of the direct venting type thereby requiring that the entire combustion process be completely sealed from the interior in that all air for combustion be drawn from the outdoors and that all flue gases and/or products of combustion be vented directly to the outdoors. However, existing direct vent systems were challenged in meeting current safety standards and were unacceptable to most users due to the fact that they (i) were difficult to install and (ii) were prone to freeze-ups and/or blow-outs and were therefore, unreliable.
Accordingly, there exists a need for an improved direct venting system for free-standing, propane refrigerators.
In accordance with an example embodiment of the present disclosure there is provided a free-standing, direct venting propane refrigerator having a storage unit for storing perishable items and a cooling unit for providing cooling to the storage unit, the refrigerator comprising a burner element for providing a gas flame for powering the cooling unit; a burner box mounted directly to a rear, exterior surface of the refrigerator for sealingly housing the burner element, the burner box having an integral mounting flange; an air intake assembly mounted directly to the rear, exterior surface of the refrigerator, the air intake assembly having a first end for drawing in fresh air from an outdoor environment and a second end coupled to said burner box for supplying the fresh air to said burner element for combustion of said gas flame; a chimney assembly mounted directly to the rear, exterior surface of the refrigerator, the chimney assembly in fluid communication with said burner box for drawing products of combustion away from the burner box; an air outlet coupled to said chimney assembly for delivering the products of combustion to the outdoor environment; wherein said burner box further comprises an air inlet adapter having a first end in direct communication with said air intake assembly and a second end in direct communication with said burner box, the first end being larger than said second end.
In accordance with another example embodiment of the present disclosure there is provided a direct venting system for a free-standing propane refrigerator, the direct venting system comprising an air intake for drawing fresh air from an outdoor environment; a burner box for housing burner elements associated with providing a heat source in the form of combustion of a propane gas flame for powering the refrigerator; a chimney assembly for drawing products of combustion away from said burner box; an air outlet for delivering said products of combustion from said chimney assembly to said outdoor environment; wherein said burner box comprises an air inlet adapter having a first end coupled to said air intake and a second end coupled to said burner box, said first end being larger than said second end for delivering air to said burner box.
In accordance with another example embodiment of the present disclosure there is provided a burner box assembly for a direct venting free-standing propane refrigerator, the burner box assembly comprising a burner box defining an open interior cavity for housing burner elements for providing a propane gas flame; an integrally formed mounting flange extending from open edges of said burner box for sealingly mounting said burner box to said refrigerator; an air intake adapter sealingly mounted to said burner box in fluid communication with said open interior cavity, the air intake adapter having a first open end for receiving fresh air from an outside environment and a second open end in fluid communication with said open interior cavity for delivering said fresh air to said open interior cavity; wherein said first open end is larger than said second open end.
In accordance with another example embodiment of the present disclosure there is provided a chimney assembly for a direct venting free-standing propane refrigerator, the chimney assembly comprising a first tubular portion; a second tubular portion laterally offset with respect to the first tubular portion; a horizontally extending tubular portion interconnecting said first tubular portion and said second tubular portion in their laterally offset relationship, the horizontally extending tubular portion forming two generally 90 degree bends with respect to said first and second tubular portions; wherein said first, second and horizontally extending tubular portions are three layered tubular members, each of which comprises an inner tubular member; an insulating member surrounding said inner tubular member; and an outer covering surrounding said insulating member.
Further objects and advantages of the present invention will be apparent from the following description, reference being made to the accompanying drawings, wherein like reference characters designate corresponding parts.
Exemplary embodiments of the present disclosure will now be described, by way of example, with reference to the accompanying drawings, in which:
Referring now to
As is generally understood in the art, during use of the propane refrigerator 10, the boiler 16 generates heat by means of a heat source such as a gas flame from a propane burner 28 (or any other suitable heat source in accordance with principles known in the art), which heat is transferred to the refrigerant solution that is fed to the boiler 16 from the absorber tank 26. The propane flame typically produces 700 to 1800 BTU as compared to a furnace which operates between 30,000 to 75,000 BTU. The refrigerant solution (i.e. the ammonia-rich refrigerant solution) begins to vaporize and travels upwards through the boiler 16 to the condenser 18 where it is cooled by air passing though the metal fins 30 of the condenser 18 forcing the ammonia or refrigerant vapour back to a liquid state where it enters the evaporator 20. In the evaporator section 20 of the cooling unit 14, heat extracted from the storage unit 12 (i.e. the refrigerator/freezer sections of the refrigerator 10) causes evaporation of the liquid ammonia or liquid refrigerant solution, which vaporized mixture is returned or drops back down to the absorber tank 26 and the refrigeration cycle continues.
As briefly described above, the refrigeration cycle begins with a heat source in the boiler 16 which begins the vaporization of the refrigerant or ammonia-rich solution. The heat source to power the absorption system can come from an electric heating element or from a flame. In remote or off-grid areas where there is no source of AC/10 electricity, propane fuels a gas flame that serves as the heat source within the boiler 16. In order to comply with government mandated safety regulations in Canada, free-standing propane refrigerators for use in residential dwellings must be of the direct vent type which requires that all of the air used for combustion purposes be taken or drawn from the outdoors with all flue gases and/or products of combustion being exhausted outdoors. The entire combustion process associated with the propane refrigerator, therefore, must not communicate with the interior environment of the building within which the refrigerator is installed.
Accordingly, the refrigerator 10 according to an example embodiment of the present disclosure is equipped with a direct venting system 40 for ensuring that any flue gases and/or products of combustion are successfully vented to the outdoors or outside the residential dwelling or building without any of the products of combustion leaking into the building or residential dwelling while ensuring proper and reliable functioning of the propane refrigerator 10. The direct venting system 40, therefore, (i) sealed so as not to allow any products of combustion to leak into the building, (ii) allows for correct air balance between the air inlet and the chimney to allow for natural venting while providing sufficient oxygen for the burners to operate and sufficient evacuation to allow continued combustion, (iii) allows for collection and dissipation of corrosive condensate (such as hydrochloric acid) in the flue system, and (iv) is also capable of operating properly and efficiently in a wide range of temperatures (−22° C. to +38° C.) as well as operate under high wind conditions (i.e. 60 kph (40 mph)).
The direct venting system 40 comprises and air intake assembly 42, a burner box 44, a flue assembly 46 and a chimney assembly 48 that are pre-assembled and pre-installed on the rear of the refrigerator 10. The burner box 44 is mounted directly to the exterior, rear surface of the refrigerator 10, the burner box 44 housing the burner elements (not shown) for the propane gas flame for heating and/or powering the refrigeration or cooling unit 14. The burner box 44, as shown in
The burner box 44 mounts directly and permanently to the frame of the refrigerator 10 with at least one bracket member 41, one of which is partially shown in
The burner box 44 further comprises an air inlet adapter 58 that is securely mounted at one end of the burner box 44 in fluid communication with the interior cavity 50. In the subject example embodiment, the air inlet adapter 58 is welded to the burner box 44 through an air inlet opening 59 formed in the end wall 47 of the burner box 44. The air inlet adapter 58 has a first end 60 for receiving air from the outdoors through the air intake 42 and a second end 62 for delivering the air to the burner box 44 for fueling or feeding the combustion process, the second end 62 being sealingly mounted to the burner box 44 in fluid communication with the air inlet opening 59. The first end 60 of the air inlet adapter 58 is generally circular and has a diameter larger than the diameter of the second end 62, which is also generally circular. A step-down region 63 interconnects the first end 60 and the second end 62. The first end 60, second end 62 and step-down region 63 are specifically designed and sized to ensure that air is delivered to the open interior cavity 50 of the burner box 44 at an appropriate angle and in a manner to ensure that proper combustion occurs within the burner box 44. If the air enters the burner box 44 through the inlet adapter 58 at too fast a rate or with increased velocity or turbulence within the air flow, or at an inappropriate angle, it risks blowing out the burner flame which effectively shuts-off the refrigerator. As well, if the air enters the burner box 44 through the adapter 58 at too slow a rate or without the proper velocity and/or turbulence within the flow, etc., combustion may not occur properly within the burner box to ensure the optimal functioning of the refrigerator 10. The transition from the first, larger end 60 to the smaller diameter second end 62 via step-down region delivers the air to the burner box 44 with the desired flow properties to greatly decrease the risk of blow-out and therefore improves the efficiency and reliability of the refrigerator 10. In accordance with one example embodiment, the second end 62 is generally about half the diameter of the first end 60 with the first end 60 having an inner diameter of about 55 mm and the second end having an inner diameter of about 29 mm.
Referring now to
The flue assembly 46 comprises a cylindrical housing 74 having a first, lower end 76 mounted to the upper surface or wall 45 of the burner box 44 and a second end 78 connected to the chimney assembly 48. The first or lower end 76 of the cylindrical housing 74 is adapted to be in fluid communication with the interior cavity 50 to receive flue gases and/or the products of combustion from within the burner box 44 while the second or upper end 78 is fluidly coupled to the chimney assembly 48 with the flue gases and/or products of combustion travelling upwards through the flue assembly 46 to the chimney assembly 48 before being vented to the outdoors through the direct venting system outlet or flue gas exhaust 80.
Referring now to
An outlet or exterior flue vent 80 is mounted to the upper end of the vertical portion 84 of the chimney assembly 48 and extends horizontally away from the back of the refrigerator 10. Like the fresh air intake 72, the exterior flue vent 80 is mounted to the chimney assembly 48 at the time of installation of the refrigerator 10, with the exterior flue vent 80 extending through the exterior wall 13 of the building, as shown in
As flue gases and/or the products of combustion travel upwards through the flue assembly 46 and chimney assembly 48, the temperature of the gases cools and the gases tend to condense and form condensate. This condensate can drip down the chimney and flue assemblies 48, 46 and back into the burner box 44, which can snuff or blow-out the burner flame causing the refrigerator 10 to shutdown. The condensate is also known to be highly acidic and corrosive. Therefore, any condensate that drips or drains down through the chimney assembly 48 and flue assembly 46 into the burner box 44 can corrode or otherwise damage any of the components of the direct venting system 40 and burner elements housed within the burner box 44 and negatively impact the functioning of the refrigerator 10.
In order to improve reliability and proper functioning of the refrigerator 10 and to protect the flue assembly 46 and burner box 44 from corrosion due to condensate, it is important to prevent and/order decrease the amount of condensate formed during operation of the propane refrigerator 10. Accordingly, the exterior flue vent 80 is formed as a three-layer insulated structure which maintains the warmer or higher temperatures of the flue gases or products of combustion as they travel upwards through the chimney assembly 48 to the exterior flue vent 80 which prevents or decreases the amount of condensate formed as the gases or combustion products travel upwards through the direct venting system 40.
As shown in
In the event that condensate does form within the chimney assembly 48 during operation or use of the refrigerator 10, a condensate trap 90 is incorporated into the direct venting system 40. The condensate trap 90 is a small diameter tubular member that is formed with a 360 degree bend therein. A first end 92 of the condensate trap 90 is mounted in fluid communication with the second vertical portion 84 of the chimney assembly 48 for receiving condensate that may drip down from the exterior flue vent or chimney assembly 48. A second end 94 of the condensate trap 90 is fluidly connected to evaporator trays (not shown) located at the bottom of the refrigerator 10 by means of any suitable tubing 95 (as shown in
While an exemplary embodiment of the direct venting system has been described and shown in the drawings, it will be understood that certain adaptations and modifications of the described exemplary embodiment can be made as construed within the scope of the present disclosure. Therefore, the above discussed embodiment is considered to be illustrative and not restrictive.