US3566957A

US3566957A - Metal-to-metal heat exchanger for recreational vehicle

Info

Publication number: US3566957A
Application number: US816640A
Authority: US
Inventors: James Earl Bridegum
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-04-16
Filing date: 1969-04-16
Publication date: 1971-03-02
Anticipated expiration: 1988-03-02

Abstract

A heat exchange unit for circulating vehicle radiator liquid is positioned in a large tank that conducts potable water so that the radiator liquid becomes cooled as the potable water becomes heated. The unit includes a container capable of being mounted to the tank and a conduit inserted in heat exchange relationship within the container. For safety purposes a narrow leakage gap is defined between the container and conduit so that any leakage of radiator liquid from the conduit will automatically flow outwardly of the tank where it will be unable to contaminate the potable water.

Description

v Un ted States Patent 1 3,566,957

'[72] inventor James Earl Bridegum [56] References Cited 12143 Gothic Ave., Granada Hills, Calif. UNITED STATES PATENTS 91344 pp No. 816,640 2,669,435 2/1954 Cord et al. l65/70X [22] Filed Apr. 16, 1969 Primary Examiner-Martin P. Schwadron [45] Patented Mar. 2, 1971 Assistant ExaminerThe'ophil W. Streule Att0rneyPastoriza & Kelly ABSTRACT: A heat exchange unit for circulating vehicle radiator liquid is positioned in a large tank that conducts potable water so that the radiator liquid becomes cooled as the [54] FOR potable water becomes heated. The unit includes a container 10 Cl 4 D capable of being mounted to the tank and a conduit inserted in arms, rawlng lg heat exchange relationship within the container. For safety [52] U.S.Cl 165/70, purposes a narrow leakage gap is defined between the con- 165/142 tainer and conduit so that any leakage-of radiator liquid from [51] Int. Cl F28f1l/00 the conduit will automatically flow outwardly of the tank [50] Field of Search 165/70, 142 where it will be unable to contaminate the potable water.

MAIN DOMESTIC 25?-/ WATER SUPPLY 26 BATHROOM TANK - PATENTEUMAR 2mm J, 22 INVENTOR.

5" JAMES EARL BRIDEGUM 33 W& FIG. 4

ATTORNEYS METAL-TO-METAL HEAT EXCHANGER FOR RECREATIONAL VEHICLE CROSS REFERENCE TO PENDING APPLICATION This application is related to a copending US. Pat. application Ser. No. 746,448 filed Jul. 22, 1968 now Pat. No. 3,521,704, granted Jul. 28, I970 and entitled HEAT EXCHANGER FOR RECREATIONAL VEHICLE.

This invention relates to a heat exchange unit and more specifically to a heat exchange unit for simultaneously heating and cooling different liquid circulating around and through the unit.

, BACKGROUND OF THE INVENTION I The concept of using the circulating radiator water of a recreational vehicle as a thermal energy source to heat domestic water is known. Some presently operated motor homes and campers link togetherthe radiator water circuit and domestic water circuit so that as the domestic water absorbs heat from the radiator water, then the radiator water automatically becomes cooled.

However, when the radiator water and domestic water circuits are integrated in this manner, a potentially serious health hazard arises. Consumers of the domestic water are constantly exposed to the possibility of having contaminated radiator water seep or leak into the domestic water. Thus far it has been impossible to isolate the domestic water and radiator water circuits and still safely take advantage of the heat exchange relationship.

Variousjresponsible governmental and certifying groups that establish exacting plumbing safety standards routinely refuse to approve presently employed vehicle heat exchange systems because they are inherently incapable of providing adequate safety for the consumers health. One cause tending to promote the leakage of radiator water into the domestic water is that the customary copper tubing for conducting the radiator water gradually erodes and deteriorates upon prolonged exposure to antifreeze solutions and other radiator water additives. When the tube becomes ruptured, radiator water leaks through the tube and becomes mixed with the domestic water. Safe plumbing practices aimed at guaranteeing wholesome water demand that this type of situation be prevented.

Another drawback of conventional vehicle heat exchange systems in campers for example, is that when the camper is replenishing its depleted domestic water supply and an undetected leak has occurred then the mixed liquid may backflow into the community water supply. Those who administer the plumbing codes are especially vigilant of this danger source and disapprove such proposed vehicle heat exchange systems Otherwise the serious deficiencies might eventually harm numerous people.

BRIEF SUMMARY OF THE INVENTION Briefly described the present invention comprehends acompact, inexpensive heat exchange unit that has no moving parts and can be easily assembled, for example, to a recreational vehicle tank that conducts potable water.

The heat exchange unit includes a metal container with a closed end and an open end, and a metal conduit having an inlet port for admitting a liquid and an exit port for discharging the liquid. The conduit is positioned in heat exchange relationship within the container and a closed conduit end is arranged adjacent a closed container end. A leakage gap is defined between the container inner wall and conduit outer wall in order to conduct any liquid outwardly of the container that leaks from the conduit into the leakage gap. The escape through the leakage gap of liquid, which may be vehicle radiator water, prevents the liquid from mingling with and contaminating potable water in the tank.

Preferably the leakage gap clearance between the container inner wall and conduit outer wall is between 0.002 inches and 0.005 inches. A flow tube extends through one of the conduit ports and into the interior portion of the conduit in order to increase the circulation path of the relatively hot radiator liquid through the conduit so that the heat transfer capacity between the conduit and container can be improved.

Preferably the flow tube extends into the conduit by a distance equivalent over percent of the end-to-end length of the conduit. A mounting flange is joined to the conduit so that the heat exchange unit can be mounted to the tank.

BRIEF DESCRIPTION OF THE DRAWINGS The numerous benefits and unique aspects of the present invention will be fully understood when the following detailed description is studied in conjunction with the drawings in which:

FIG. 1 is a schematic view showing a vehicle radiator circuit interconnected by way of the heat exchanger of the present invention with a typical recreational vehicle plumbing system;

FIG. 2 is a perspectivepartially sectional view showing the conduit component partially inserted into the container component of the heat exchange unit;

FIG. 3 is a longitudinal cross-sectional view of the container and conduit components fully assembled; and

FIG. 4 is a schematic view showing the simultaneous flow of vehicle radiator water through the heat exchange unit and potable water through the tank.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT- Referring to FIG. 1, there is shown a fire wall 10 or other support partition incorporated in a recreational vehicle such as a motor home, camper or pleasureboat. The vehicle includes a customary engine block 11 and radiator 12 that may be filled withwater and various chemical compounds such as antifreeze not fit for human consumption when a radiator cap 13 is removed. A conventional fan 14 is mounted to the forward wall of engine block 11. A supply hose 15 conducts radiator water into a manifold within engine block 11 and a return hose 16 returns heated water from block 11 to radiator 12.

A flow line for circulating radiator water includes a radiator exit flow line 17 having sections that may be disconnected by an intermediate coupling'l8, and, a radiator inlet flow line 19 having a similar intermediate coupling 20 for disconnecting segments ofline 19. Lines 17 and 19 are arranged to circulate radiator liquid through a portion of a heat exchange system 21. Heat exchange system 21 includes a tank 22 which mounts a heat exchange unit 23 coupled to a mounting member 24.

Heat exchange system 21, as shall be fully explained interconnects the radiator water circuit with the vehicle plumbing circuit which conducts domestic or potable water suitable for cleansing and human consumption. Potable water from a main supply domestic water tank 25 is channeled by a pump or compressor 26 through a main flow line 27. Extending from main flow line 27 is a first cold water branchline 28 leading to a bathroom 29 and a second cold water branch line 30 leading to a sink 31 which may be located in the vehicle kitchen, bathroom or any other convenient location. Potable water flowing downstream of line 30 may be discharged through a drain valve 32 or through a flow line 33 to tank 22. Extending from the top part of tank 22 is a tank exit flow line 34 for supplying heated water to a riser 35. From riser 35 heated water may be supplied to sink 31 through line 36 and/or bathroom 29 through another line 37.

FIG. 2 illustrates important details of heat exchange unit 23 which is constructed of two main components. A metal container 38 is of tubular shape and has an open end 39 and'a closed end 40. Open end 39 is joined to a mounting flange 41 formed with a series of mounting openings 42 can be used to mount heat exchange unit 23 to a tank, such as tank 22shown in FIG. 1.

i and 47

areflow tubes

48 and 49 respectively. When conduit 43.is fully slid into container 38 and heat exchange unit 23 is in operation then radiator water may flow inwardly through flow tube48, as indicated by directional arrow 50, and outwardly through flow tube 49, as indicated by directional arrow IG. 3 shows heat exchange unit 23 fully assembled and ready for use. Conduit closed end 44 is arranged adjacent container closed end.40 and conduit closed end 45 is arranged adjacent container open end 39. Container 38 and conduit 43 are relatively sized so that the interior wall of container 38 and exterior wall of conduit 43 are positioned in heat exchange relationship and define a leakage gap 52. Both conduit 43 and v 38 are constructed of metal with outstanding heat transfer characteristics such as copper, aluminum or brass.

The width of leakage gap 52 is sufficiently small so that the heat transfer capacity and efficiency between container 38 and conduit 43 is adequate and is sufficiently large so that the leakage of any liquid such as contaminated vehicle radiator water from conduit 43 must enter gap52 and then pass outwardly of unit 23. The aim is to prevent contaminated or offensive liquid circulating through conduit 43 from mixing with potable water surrounding container 38. The width of leakage gap 52,.which is sufficiently small for heat transfer purposes and sufficiently large to permit the leakage or escape of offensive liquid is between 0.002 inches and 0.005 inches.

Flow tube 49 is coupled in fluid communication with port 47 and does not extend into conduit 43. In comparison flow tube 48 extends through port 46 and has an extension 53 that projects into the interior of conduit 43. The purpose of extending only one flow tube into the interior of conduit 43 is to increase the circulation path of liquid flowing through conduit 43. in order to increase the overall heat transfer capacity between conduit 43 and container 38.

The length of extension 53 is preferably between 85 percent and 97 percent of the end-to-end length of conduit 43. By this arrangement a greater quantity of thermal energy has an opportunity to be transferred across the metalto-metal interface defined by container 38 and conduit 43.

If extension 53 were eliminated then, it will be appreciated, a sharp heat transfer gradient would result across the end-toend length of the metal-to-metal interface between conduit 43 and container 38. Maximum heat transfer would occur adjacent conduit outer end 45 and the heat transfer efficiency would gradually diminish to a minimum heat transfer value adjacent conduit inner end 44. The use of extension 53 causes more heat to be liberated from liquid circulating through conduit 38 to liquid surrounding container 38. It should be noted that the liquid circulating through heat-exchanger 23 may be either hotter or colder than the liquid surrounding heat exchange unit 23, and, liquid may enter flow tube 49 and exit through flow tube 48 or vice versa. I

Referring now to FlG. 4, tank 22 has a space which together with tank inlet line 33 and tank exit line 34 constitutes a part of the main domestic flow line 27 shown in FIG. 1.

Heat exchange unit 23 is mounted by its flange 41 and bolts to a wall of tank 22. Installed on one side of tank 22 is a gas water heater 54 which may be operated to heat the potable liquid circulating through tank 22 when the vehicle engine is not running. Heater 54 which-may be a conventional propane heater includes the usual controls 55, main gas supply tube 56,

pilot gas tube 57 and thermocouple 58 for sensing the- OPERATION Keeping the above construction in mind it can be understood how many disadvantages of conventional vehicle heat exchange systems are overcome or substantially eliminated by the present invention.

In order to prepare heat exchange unit 23 for actual use in its intended environment, metal conduit 43 is slid into metal container 38, mounting flange 41 is fixed to an appropriate wall portion of tank 22, and, then flow

tubes

48 and 49 are coupled to different flow segments of the radiator water circuit as indicated in FIG. 1.

When the recreational vehicle motor is running circulating radiator water passes through flow tube 49, (referring to FIG. 4), travels approximately the end-to-end length of metal conduit 43, reverses its path and travels through extension 53, and, eventually exits through flow tube 48. As the radiator water progresses through heat exchange unit 23 thermal energy is liberated by the radiator water and is absorbed by the domestic water passing through tank 22. Domestic water enters tank 22 through flow line 33, and, after circulating around heat exchange unit 23, departs through exitflow line 34. As the domestic water acquires thermal energy from the radiator water, due to the metal-to-metal contact between container 38 and conduit 43, the radiator water automatically becomes cooled in order to improve the operating efficiency of the vehicle engine.

If intense pressure, metal deterioration, inherent defects or the like cause an inner wall portion of conduit 43 to rupture and develop a leakage passage then, in accordance with safety aspects of this invention, the risk of toxic radiator water contaminating the domestic water is prevented. Radiator water flows into the narrow leakage gap 52 and, due to the radiator water pressure, is driven through leakage gap 52 outwardly of heat exchange unit 23. The vehicle driver will be notified of the leakage condition by a conventional vehicle dashboard gauge that is responsive to engine overheating or reduced pressure.

From the foregoing it will be evident that the present invention has provided a metal-to-metal heat exchange unit for recreational vehicles in which all of the various advantages are fully realized.

I claim:

1. A vehicle heat exchange system for simultaneously heating potable liquid from a potable liquid source and cooling radiator water circulating through the vehicle radiator circuit, the system comprising:

a. a tank having inlet and exit lines for admitting and discharging potable liquid;

b. a metal container mounted to and projecting into the tank, the container being arranged in heat exchange relationship with the tank;

0. a vehicle radiator flow line segment;

d. a metal conduit coupled to the radiator vehicle flow line segment and having an inlet port for admitting radiator water and an exit port for discharging radiator water, the conduit being positioned within the container and in metal-to-metal heat exchange relationship therewith throughout the major portion of its length; and

e. means defining a leakage gap between the container and conduit for conducting any radiator water that might leak from a portion of the conduit position within a container to a location outwardly of the container.

2. The structure according to claim 1, wherein; the average clearance between the container inner wall and conduit outer wall is between 0.002 inches and 0.005 inches.

3. The structure according to claim 1, including; a flow tube extending through one conduit port and into the interior of the conduit, the flow tube being arranged to increase the circulation path of radiator water through the conduit in order to increase the heat transfer capacity between the conduit and container.

port.

6. The structure according to claim 1, wherein:

the container has a closed end and an open end for receiving the conduit; and

the conduit has a closed end arranged adjacent the container closed end and a second end that forms the fluid inlet and exit ports.

7. The structure according to claim 6, wherein:

the container is of tubular cross section;

a mounting flange is joined to the container open end;

the conduit is of tubular cross section and has a length substantially equivalent with that of the container, and

the leakage gap is of annular configuration. I

8. A vehicle heat exchange system for simultaneously heating potable liquid from a potable liquid source and cooling radiator water circulating through the vehicle radiator circuit, the system comprising:

b. a metal container having a closed end and an open end, the container being mounted to and projecting'into the tank and arranged in heat exchange relationship with the tank;

c. a vehicle radiator flow line segment;

(1. a metal conduit coupled to the radiatorvehicle flow line segment and having an inlet port for admitting radiator water and an exit port for discharging radiator water, the conduit being positioned within the container and in metal-to-metal heat exchange relationship therewith throughout the major portion of its length;

. a flow tube extending through one conduit port and into the interior of the conduit, the flow tube being arranged to increase the circulation path of radiator water through the conduit in order to increase the heat transfer capacity between the conduit and container; and

f. means defining a leakage gap between the container and conduit for conducting any radiator water that might leak from a portion of the conduit positioned within the container to a location outwardly of the container, the average width of the leakage gap being between 0.002 inches and 0.005 inches.

9. The structure according to claim 8, wherein; the flow l tube extends over percent of the end-to-end distance of the conduit.

10. The structure according to claim 9, including:

a tank for conducting potable liquid, the metal container being mounted to the tank so that the major portion of the conduit projects into the tank and the leakage gap terminates outwardly of the tank; and

wherein, when relatively high vehicle radiator water is circulated through the conduit and relatively cool potable is circulated through the tank the heat exchange relationship between the conduit and container simultaneously causes the potable water to become heated while the radiator liquid becomes cooled.

Claims

2. The structure according to claim 1, wherein; the average clearance between the container inner wall and conduit outer wall is between 0.002 inches and 0.005 inches.
3. The structure according to claim 1, including; a flow tube extending through one conduit port and into the interior of the conduit, the flow tube being arranged to increase the circulation path of radiator water through the conduit in order to increase the heat transfer capacity between the conduit and container.
4. The structure according to claim 3, wherein; the flow tube extends over 90 percent of the end-to-end distance of the conduit.
5. The structure according to claim 4, including; a second flow tube coupled in fluid communication to the other conduit port.
6. The structure according to claim 1, wherein: the container has a closed end and an open end for receiving the conduit; and the conduit has a closed end arranged adjacent the container closed end and a second end that forms the fluid inlet and exit ports.
7. The structure according to claim 6, wherein: the container is of tubular cross section; a mounting flange is joined to the container open end; the conduit is of tubular cross section and has a length substantially equivalent with that of the container, and the leakage gap is of annular configuration.
8. A vehicle heat exchange system for simultaneously heating potable liquid from a potable liquid source and cooling radiator water circulating through the vehicle radiator circuit, the system comprising: a. a tank having inlet and exit lines for admitting and discharging potable liquid; b. a metal container having a closed end and an open end, the container being mounted to and projecting into the tank and arranged in heat exchange relationship with the tank; c. a vehicle radiator flow line segment; d. a metal conduit coupled to the radiator vehicle flow line segment and having an inlet port for admitting radiator water and an exit port for discharging radiator water, the conduit being positioned within the container and in metal-to-metal heat exchange relationship therewith throughout the major portion of its length; e. a flow tube extending through one conduit port and into the interior of the conduit, the flow tube being arranged to increase the circulation path of radiator water through the conduit in order to increase the heat transfer capacity between the conduit and container; and f. means defining a leakage gap between the container and conduit for conducting any radiator water that might leak from a portion of the conduit positioned within the container to a location outwardly of the container, the average width of the leakage gap being between 0.002 inches and 0.005 inches.
9. The structure according to claim 8, wherein; the flow tube extends over 90 percent of the end-to-end distance of the conduit.
10. The structure according to claim 9, including: a tank for conducting potable liquid, the metal container being mounted to the tank so that the major portion of the conduit projects into the tank and the leakage gap terminates outwardly of the tank; and wherein, when relatively high vehicle radiator water is circulated through the conduit and relatively cool potable is circulated through the tank the heat exchange relationship between the conduit and container simultaneously causes the potable water to become heated while the radiator liquid becomes cooled.