WO2003098123A2

WO2003098123A2 - Heating system

Info

Publication number: WO2003098123A2
Application number: PCT/US2003/015587
Authority: WO
Inventors: Cristian Murgu; James M. Rixen
Original assignee: North-West Research & Development, Inc.
Priority date: 2002-05-14
Filing date: 2003-05-14
Publication date: 2003-11-27
Also published as: WO2003098123A8; CA2525633A1; US20030234296A1; WO2003098123A3; AU2003237885A8; AU2003237885A1

Abstract

A water heater system (10) uses a heated fluid storage tank (26) to deliver a continuous supply of water heated to a desired temperature, such as between 100°-130° F. The system also includes a furnace with altitude-sensitive control circuitry to provide multiple sources of heat for the heating system in the most effective way given the altitude at which the system is located. The system also includes a micro-controller that adjusts certain system components in response to changes in atmospheric pressure conditions that are measured by an atmospheric-pressure sensor component. There is also an automatic-air-bleeder subsystem with an optical or ultrasonic sensor mounted adjacent a suitable air accumulator. Also included is an air-release solenoid and a fuel return line.

Description

HEATING SYSTEM

Cross-Reference to Related Applications

This application is a continuation-in-part of U.S. Patent Application Serial

No. 10/421,365, filed April 22, 2003 entitled "Heating System", and incorporated herein by

reference. This application also claims priority to U.S. Provisional Patent Application Serial

No. 60/380,586, filed May 14, 2002 and entitled "Heating System".

Field of the Invention

The present invention relates generally to heating systems, and more specifically, to a

hydronic heating system and method for recreational-vehicle (RV), marine and home heating applications that includes a system for altitude compensation for diesel-fire heaters,

and an automatic air bleeder for removing unwanted air bubbles from heater fuel.

Background of the Invention

Heating systems for campers and recreational vehicles are widely known.

Conventional water heating systems for recreational vehicles generally fall into two classes.

The first class includes systems that have a heating element(s) that extends into a cavity that

holds several gallons of water. The heating element ultimately heats the entire volume of

water in the cavity. Drawbacks to this first class include a lack of continuous hot water. In

addition, the first class of systems takes a relatively long period of time to heat water. The

second class involves systems that heat a relatively small volume of water with a gas or

electric heating device. Conventional systems of the second class include propane, or other

open flame "flash furnace" heating systems that directly heat domestic water supplied to the

system. Open-flame systems like these are relatively expensive and relatively unsafe when

used in a recreation vehicle. In addition, a propane system is ineffective to provide a

constant supply of hot water. For heating devices used in the above heating systems, there are certain problems

caused when changes in atmospheric pressure (due to changes in altitude or weather)

undesirably affects heating-fuel combustion. Conventional heating devices (heaters) are

not constructed to change the combustion parameters,^" and as a result they do not perform

optimally when such changes occur. The result is that heater exhaust emissions increase

causing smoke, and giving off undesirable smells/odors. Carbon also accumulates on the

heater-burner tube and other system components. Overall, conventional heater

performance/efficiency becomes low, maintenance becomes expensive, and ultimately the

heater becomes damaged.

Accordingly, for applications where the heater is used in different atmospheric

pressure conditions, there is a need for the heater to be constructed to adjust combustion

parameters based upon changes in atmospheric pressure to maintain low exhaust

emissions (e.g. Recreational Vehicle (RN) and household applications), maintain optimal performance, and reduce the risk of heater damage or need for maintenance.

Generally, conventional diesel-fired heaters can characterized as high-pressure and

low-pressure, where the pressure (high or low) refers to the pressure between the fuel

pump and the fuel-atomizing device associated with the heater. In connection with low-

pressure diesel-fired heaters for RN, there have been conventional proposals to deal with the situation where the RN (and heater) increase altitude by using a so-called zero-

pressure regulator and a Nenturi fuel-atomizing system to reduce the amount of fuel

which is burned in the combustion process at higher altitude. One drawback to this

method is that heat output/efficiency drops with each incremental increase in altitude at

an approximate rate of 5% for every 3000 ft.

Another problem associated with conventional diesel-fired heaters is that the

associated fuel pump supplies fuel that is mixed with undesirable air bubbles. Passing through the fuel-atomizing component of conventional systems, these air bubbles cause

gaps in the fuel supply which can cause heater de-activation (so-called "flame out"

conditions). When the heater flames out, a white cloud of smoke is generated because

conventional control circuitry cannot immediately stop the fuel-delivery subsystem. As a

result, fuel is sprayed into a hot combustion chamber for a period of time. This situation

causes the smoke, or in the worst case where the fuel re-ignites, explosions.

Objects of the invention include solving the problems associated with changes in

atmospheric conditions, and those associated with air bubbles in the heater fuel.

Summary of the Invention

The present invention overcomes the drawbacks of conventional systems by

providing a water heating system that uses a heated fluid storage tank to deliver a continuous

supply of water heated to a desired temperature, such as between 100°-130°F. The system

also may combine a heated fluid storage tank with an altitude sensitive burner type furnace

to provide multiple sources of heat for the heating system.

To achieve the desired altitude compensation capability, the system includes a

controller (preferably a micro-controller) that adjusts certain system components in response

to changes in atmospheric pressure conditions that are measured by an atmospheric-pressure

sensor component of the invention. For example, for low-pressure-type diesel-fired heaters,

the invention is constructed to increase the amount of combustion air in response to a sensed

increase in altitude. By increasing the pressure of the compressed air so that changes in

altitude will not affect the quantity of fuel absorbed through the heater nozzle (under

Nenturi effect), the altitude-compensation controller (or circuit) of the invention will

adjust the amount of the combustion air by controlling the sped of the combustion fan or

the surface (size) of the combustion-air-intake opening. This controller and method

maintains a constant heat output regardless of changes in atmospheric pressure such as changes in altitude or weather.

The automatic air bleeder of the invention includes a suitable sensor (such as an

optical or ultrasonic one) mounted adjacent a suitable air accumulator (for optical sensors,

substantially transparent or clear glass, or a plastic tube are suitable; for ultrasonic

sensors, plastic or rubber tubes are suitable). Also included is an air-release solenoid and

a fuel return line.

Brief Description of the Drawings

Figs. 1 is a schematic diagram of a heating system according to one embodiment

of the present invention.

Fig. 2 is a schematic diagram of an altimeter connected to the motor of a fan

usable in the heating system of the invention.

Fig. 3 is a schematic diagram of an altimeter with a flash micro-controller of the

invention.

Fig. 4 is a schematic diagram of an automatic air-bleeder feature of the invention.

Fig. 5 is a schematic diagram showing a heater feature of the invention for use in

applications for low-pressure-type heaters and that shows altitude compensation via fan-

speed control.

Fig. 6 is a schematic diagram showing a heater feature of the invention for use in

applications for low-pressure-type heaters and that shows altitude compensation via

control of the combustion-air- intake surface.

Fig. 7 is a schematic diagram showing a heater feature of the invention for use in

applications for high-pressure-type heaters and that shows altitude compensation via

controlling the flow of fuel from the fuel pump.

Fig. 8 is a schematic diagram showing a heater feature of the invention for use in

applications for high-pressure-type heaters and that shows altitude compensation via control of the combustion-air- intake surface.

Fig. 9 is a schematic diagram showing a heater feature of the invention for use in

applications for high-pressure-type heaters and that shows altitude compensation via fan-

speed control.

Detailed Description and Best Mode of the Invention

A heating system according to one embodiment of the present invention is shown

at 10 in Fig. 1. The heating system may be used to provide a continuous supply potable

hot water, and to provide heat to a coach or recreational vehicle. Additionally, the heating

system may be used to warm the engine block of a coach in cold weather climates to

make the engine easier to start.

Heating system 10 uses a main heating fluid circuit 12 to provide heat for the potable hot water system, the coach heater system, and to warm the coach engine block in

cold climates. A main circuit pump 13 circulates heating fluid through circuit 12. The main heating fluid circuit 12 includes a heater/boiler 14 configured to heat a volume of

heating fluid. Typically, the heater/boiler is configured to heat a heating fluid such as

glycol; however, a mixture of glycol and water or other suitable high-heat-capacity liquid

may be used as a heating fluid.

Still referring to Fig. 1, a diesel-fired burner 15 may heat heater boiler 14. A

variable speed fan may provide burner 15 with air for combustion of diesel fuel. The

variable speed fan may be connected to an atmospheric pressure sensor, as shown at 16 in

Fig. 2. Atmospheric sensor 16 produces an electronic signal based on the external

atmospheric pressure. The electronic signal is amplified at amplifier 18 and the signal is

then processed in a signal-conditioning circuit 20. Additional signal conditioning may be

applied at 22 in the form of a PWM, DC-DC converter, voltage regulator, or frequency

inverter. Finally the signal is sent to a variable-speed motor 24. Variable-speed motor 24 drives a fan, as shown in Figs. 5-9, that supplies air for combustion to diesel-fired burner

15. As the atmospheric pressure sensor senses lower ambient air pressure it may increase

the speed of variable-speed motor 24. Increasing the speed of the motor increases the

amount of air blown in to the combustion chamber of the burner. The atmospheric

pressure sensor may continuously vary the speed of the fan in response to changes in the

atmospheric pressure.

Alternatively, the atmospheric pressure sensor may speed up the fan to increase

the flow of air to the burner at discrete altitudes where ambient air pressure drops below

specific thresholds. For example, from sea level to 2000 ft. the fan speed may be low.

Above 2000 ft. up to around 6000 ft. the fan speed may be medium or higher than the low

setting. Above 6000 ft. the fan speed may be high to compensate for the lower density of

air at that altitude.

Referring again to Fig. 1, main heating fluid circuit 12 further includes a heated

expansion tank 26. Tank 26 may be heated by electric heating elements 28. A suitable

heated expansion tank 26 is available commercially under the trade name

COMFORTHOT^tm Typically, heating elements 16 are 2-kilowatt electric heating

elements; however, any suitable heating element may be used. Heating elements 28 are

inserted into tank 26 in a manner similar to a conventional residential electric hot water

heater. Heat energy is stored in the tank 26, so in a sense tank 26 acts as a heat battery for

the heating system capable of providing instant heat energy to any system that requires it.

The electric elements maintain the heating fluid at an elevated temperature without a

large energy demand, while there is little or no demand for heat from the system. As

demand for heat increases burner 15 of tank 26 is activated and thus provides additional

heat energy for heating water ultimately for use as shower water or as heating fluid that is

used to heat the vehicle cabin or engine block. , Main heating fluid circuit 12 also includes a domestic water heat exchanger 32.

Heating fluid in the main heating circuit flows through domestic water heat exchanger 32

to heat water. Water in the domestic water system is heated by transferring heat from the

heating fluid to domestic water in heat exchanger 32.

Domestic water system 34 supplies cold water to heat exchanger 32 for heating.

The heated water exits heat exchanger 32 and flows to a mixing valve 36 that prevents hot

water from exceeding a certain temperature by mixing hot water from heat exchanger 32

with cold water from the domestic water system.

Still referring to Fig. 1, heating system 10 includes an engine-hookup loop 38, an

engine-hookup-loop pump 40 and an engine-heat exchanger 42. Main heating fluid circuit

12 flows through one side of engine-heat exchanger 42. The engine-hookup loop and

engine-heat exchanger may be used to extract excess heat from the engine of the coach

while it is operating. Opening engine-hookup loop 38 supplies engine coolant to one side of heat exchanger 42. Heat exchanger 42 transfers engine heat to the heating fluid in

main heating fluid circuit 12. Extracting heat energy from the coach's engine reduces the

energy demands of the heating system.

Another benefit of engine-hookup loop 38 is that the heating system may be used

to warm the engine block of the coach prior to starting the engine in cold climates. By

pumping engine coolant through engine-heat exchanger 42 at the same time the heating

fluid is circulating in circuit 12, heat is provided to the engine of the recreational vehicle.

Preheating an engine block in cold climates makes it easier to start and reduces wear and

tear on the engine.

A cabin-heating loop 44 may by attached to main-heating-fluid circuit 12 that

supplies heating fluid to heating fans (not shown) in the cabin of the vehicle to provide

the cabin of the vehicle with heat. A cabin-loop solenoid 46 opens and closes the cabin loop to selectively provide the cabin with heat. Fluid pump 13 provides the pressure to

circulate heating fluid through the cabin-heating loop when the cabin loop solenoid is

open. Each heating fan acts as a heat exchanger to warm air in the cabin.

Referring to Fig. 4, an air bleeder subsystem is shown that is connectable within

the fuel line that draws fuel for the diesel-fired heater (burner)(see Figs. 5-9 below the

fuel regulator and between the fuel pump and the fuel atomizing system). The air bleeder

subsystem includes any suitable sensor, such as an optical air/air-bubble detector or

ultrasonic sensor configured to detect a bubble in the fuel line. When a bubble is detected

an air release solenoid opens the return line to bleed air back to the tank or out a vent. The

bubble detector then detects that the bubble is no longer present and the solenoid closes

the return line. The air bleeder enables the burner to run safely. Large air bubbles can

extinguish the burner flame causing clouds of white smoke, exhaust emissions, carbon

built-up and increase the cost of maintenance. In addition, re-igniting the burner flame

repeatedly can damage the burner and cause premature wear.

Referring to Figs. 5-6, the heating system of the invention is shown including the

micro-controller (Fig. 3). The heating system may be thought of as a heat-management

system designed to optimize three sources of heat. Heat may be generated from a vehicle

engine, a diesel furnace associated with a vehicle, or an electric-heating element. Heat is

stored in heating fluid and used either to heat water (to be used by vehicle users for

showering/washing) or to heat desired areas of the vehicle by directing the heating fluid

through associated pipes. A control board is used to control delivery of heat and other

decisions about the heat-management system. For example, the system may activate

various heat sources to respond to desired heat demands, such as a requirement for hot

shower water. Additionally, the control board may be configured to select one of several

heat sources (for example, electricity via a suitable AC outlet, a burner, or from the vehicle engine itself). While the vehicle is operating, the vehicle's engine may be the best

most efficient source of heat for the demands of the system. The burner (which may be

diesel powered) provides a heat source where electricity is unavailable. The system may

monitor a variety of sensors for determining the level and temperature of heating fluid

(e.g. glycol) in the heating system.

Altitude compensation feature of system and method invention.

Still referring to Figs. 5-9, the heating system of the invention is shown for use

with either low-pressure or high-pressure diesel-fired heaters (Figs. 5-6 for low-pressure

ones and Figs. 7-9 for high-pressure ones). Referring to Fig. 5, an electronic atmospheric pressure sensor is connected to a micro-controller via an amplifier and suitable auxiliary

conditioning circuitry. The controller is programmed to control the speed of a

combustion fan (which^' provides a quantity of combustion air) or to control the

surface/size of an air-intake opening while maintaining the speed of the combustion fan

constant. The micro-controller is suitably programmed automatically to: (i) increase the speed of the combustion fan or the surface of the air-intake opening (also referred to as an

orifice) upon receiving signal information from the altimeter/atmospheric-change sensor

that the atmospheric pressure is lower (higher altitude or cold weather); or (ii) decrease

the speed of the combustion fan or the surface of the air-intake opening if the altimeter

sends signal information that atmospheric pressure is higher (lower altitude/warmer

weather). In other words, based upon signal information from the altimeter that an

incremental change in atmospheric pressure has occurred, the micro-controller is

constructed automatically to change the speed of the combustion fan or the surface of the

air intake orifice (increase for higher altitude/colder weather or decrease for lower

altitude/warmer weather). The adjustment to the combustion air (speed of the combustion fan or surface of

the air intake) is experimentally determined for each application and then suitably stored

in the memory of the micro-controller via suitable data-entry components such as a

keypad. Using a micro-controller (and preferably a flash micro-controller) and

customizable software for programming the micro-controller, the same hardware can be

used for all the possible applications of low- or high- pressure heaters.

According to the system and method of the invention, for high-pressure heaters the

fuel delivered to the fuel-atomizing subsystem is maintained substantially constant

relative to atmospheric-pressure changes (altitude or weather changes). To maintain the

same heat output, the same system and method as described for low-pressure heaters is

utilized. If the desired application calls for lower heat output in lower atmospheric

pressure conditions, the system and method of the invention is constructed to control the

amount of fuel delivered using the same hardware as described above and shown in Figs. 5-9 (atmospheric pressure sensor, amplifier, conditioning circuitry and micro-controller)

in conjunction with a fuel metering device such as a fuel-metering pump or a fuel- metering valve.

Automatic air bleeder

Referring back to Fig. 4, the automatic air bleeder of the invention includes a

suitable sensor (such as an optical or ultrasonic one) mounted adjacent a suitable air

accumulator (for optical sensors, substantially transparent or clear glass, or a plastic tube

are suitable; for ultrasonic sensors, plastic or rubber tubes are suitable). Also included is

an air-release solenoid and a fuel return line.

To operate the automatic air bleeder, once the air in the air accumulator tube

reaches the level of the sensor, a pulse is generated by the conditioning circuitry and the

air release solenoid will be open for short time to release the air accumulated into the air accumulator. The duration of the pulse generated by the conditioning circuitry is

proportional to the size of the air bubble detected. A return-fuel line is mandatory for

safety reasons because when the air-release solenoid opens, a small amount of fuel is

released back into the fuel tank. If there is no air in the fuel line, then the solenoid is

closed (as it is when the fuel pump is deactivated/OFF).

The disclosure set forth above encompasses multiple distinct inventions with

independent utility. While each of these inventions has been disclosed in its preferred

form, the specific embodiments thereof, as disclosed and illustrated herein, are not to be

considered in a limiting sense as numerous variations are possible. The subject matter of

the inventions includes all novel and non-obvious combinations and sub-combinations of

the various elements, features, functions and/or properties disclosed herein.

Claims

WE CLAIM:

1. A heat management system connectable to a hydronic heating system that

includes a combustion fan and a combustion-air-intake opening, comprising:

an atmospheric-pressure sensor capable of sending signal information

about changes in atmospheric pressure; and

a controller coupled to the sensor and programmed to control the speed of

the combustion fan based upon signal information received from the sensor.

2. The system of claim 1 wherein the controller is programmed to control the

size of the opening while maintaining the speed of the combustion fan constant.

3. The system of claim 1 wherein the controller is a micro-controller:

4. The system of claim 2 wherein the controller is a micro-controller.

5. The system of claim 3 wherein the micro-controller is programmed

automatically to increase the speed of the combustion fan upon receiving signal

information from the sensor that the atmospheric pressure is lower and to decrease the

speed of the combustion fan if the sensor sends signal information that atmospheric

pressure is higher.

6. The system of claim 4 wherein the micro-controller is programmed

automatically to increase the size of the opening upon receiving signal information from

the atmospheric-change sensor that the atmospheric pressure is lower and to decrease the

size of the opening if the sensor sends signal information that atmospheric pressure is

higher.

7. A heat management system connectable to a hydronic heating system that

includes a combustion fan and a combustion-air-intake opening, comprising:

an atmospheric-change sensor capable of sending signal information about

changes in atmospheric pressure; and

a controller coupled to the sensor and programmed automatically to change

the speed of the combustion fan based upon signal information received from the sensor

that an incremental change in atmospheric pressure has occurred.

8. The system of claim 7 wherein the controller is programmed to change the size of the opening while maintaining the speed of the combustion fan constant based

upon signal information received from the sensor that an incremental change in

atmospheric pressure has occurred.

9. A heat management system connectable to a hydronic heating system with control circuitry, comprising:

an automatic air bleeder including a sensor mounted adjacent an air

accumulator and structured to send signal information to the control circuitry; and

wherein the control circuitry is coupled to the air bleeder to activate it upon

receiving signal information from the sensor.

10. The system of claim 9 wherein the sensor is chosen from the group

consisting of an optical or ultrasonic sensor.

11. The system of claim 9 wherein the accumulator is chosen from the group

consisting of substantially transparent glass, clear glass, a plastic tube, or a rubber tube.

12. The system of claim 9 further including an air-release solenoid and a fuel

return line.

13. The system of claim 10 further including an air-release solenoid and a fuel

return line.

14. The system of claim 11 further including an air-release solenoid and a fuel

return line.

15. A heat management system connectable to a hydronic heating system that

includes a fuel-metering device, comprising:

an atmospheric-pressure sensor capable of sending signal information

about changes in atmospheric pressure; and

a controller coupled to the sensor and programmed to control the amount of

fuel delivered to the system via the fuel-metering device based upon signal information

received from the sensor.