# US 8,772,681 B2 · Method and apparatus for forced air heater measurement and control

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- Number: US 8,772,681 B2
- Document ID: US8772681B2
- Status: Granted
- Kind: B2
- Application number: 11/940,682
- Filed: 2007-11-15
- Published: 2009-05-21
- Granted: 2014-07-08
- Earliest claimed: 2007-11-15
- Assignees: Electronic Instrumentation and Technology, Inc.
- Applicants: Joe T. May
- Inventors: Joe T. May
- Web page: https://patentgrep.com/patent/US8772681B2

## CPC

- F24D 5/02: operating with discharge of hot air into the space or area to be heated
- B22F 1/068: Flake-like particles
- B22F 1/10: Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
- F24D 19/1084: {for air heating systems}
- F24H 3/022: {using electric energy supply}
- F24H 3/0411: {for domestic or space-heating systems}
- F24H 9/2064: {for air heaters}
- F24H 15/204: Temperature of the air before heating
- F24H 15/238: Flow rate
- F24H 15/281: Input from user
- F24H 15/31: of valves having only one inlet port and one outlet port, e.g. flow rate regulating valves
- F24H 15/35: Control of the speed of fans
- F24H 15/37: of electric heaters
- F24H 15/414: using electronic processing, e.g. computer-based
- H05K 9/0083: {comprising electro-conductive non-fibrous particles embedded in an electrically insulating supporting structure, e.g. powder, flakes, whiskers (H05K9/0086 takes precedence)}
- H05K 9/0088: {comprising a plurality of shielding layers; combining different shielding material structure}
- B22F 2998/10: Processes characterised by the sequence of their steps
- F24H 15/148: Assessing the current energy consumption
- F24H 15/395: Information to users, e.g. alarms
- F24D: DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR (using steam or condensate extracted or exhausted from steam engine plants for heating purposes F01K17/02)
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- F24H: FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL (steam generation F22)
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## Abstract

A blower urges an airflow, at a rate according to a user-controlled flow rate command, through an electric heater and the electrical heater heats the airflow at a heater power based on a user-input temperature command, the user-input flow rate command, and a measured mass flow rate of the airflow. The heater power is calculated based on the heat energy required to heat air to the given reference temperature, at a flow rate corresponding to the measured mass flow rate. Optionally, the temperature of the air entering the electric heater is measured, and the heater power is calculated based on the heat energy required to heat air from the measured temperature to the given reference temperature, at a flow rate corresponding to the measured mass flow rate.

## Claims

### Claim 1

A system for outputting heated air at a controlled temperature and flow rate, comprising: an inlet and an outlet; an electric air blower for urging a flow of air; an electric air heater including an electric resistance element upstream of the outlet; a conduit for conducting air from said electric blower to the electric heater; a mass flow sensor connected upstream of an input of the electric air blower in a direction opposite the flow of air for generating a mass flow measurement signal MassFlow; a temperature sensor connected to an inlet of the electric air heater for generating an input temperature signal TempIN representing an input temperature; a heater power control circuit for controlling electric power to said electric air heater in response to a first control signal;
means for controlling mass flow through said electric air heater in response to a second control signal; and a controller receiving the mass flow measurement signal MassFlow and the input temperature signal TempIN and having a user input for inputting a temperature command signal TempCMD and a volume command signal VolumeCMD used by the controller for outputting air at a controlled temperature, said controller computing
TempCMD=TempIN+ΔT,
TempCMD=TempIN+((K×PowerIn/MassFlow)), and
PowerIn=(TempCMD−TempIN)×MassFlow/K,
and generating said first and second control signals, wherein the temperature sensor is arranged at the inlet of said electric air heater for generating said input temperature signal TempIN.

### Claim 2 (depends on 1)

The system recited in claim 1, wherein the temperature sensor is arranged between an output of said electric air blower and the inlet of said electric air heater for generating said input temperature signal TempIN.

### Claim 3 (depends on 1)

The system recited in claim 1, wherein said input temperature signal: TempIN is input as an ambient air temperature.

### Claim 4 (depends on 1)

The system recited in claim 1, wherein the means for controlling mass flow through said electric air heater comprises a blower control for controlling a volume of air flow produced by said electric air blower.

### Claim 5 (depends on 1)

The system recited in claim 1, wherein the means for controlling mass flow through said electric air heater comprises a controllable air valve or throttle positioned between an output of said electric air blower and the inlet of said electric air heater.

### Claim 6 (depends on 1)

The system recited in claim 1, wherein an
and the means for controlling mass flow through said electric air heater is a controllable air valve or throttle positioned between an output of said electric air blower and the inlet of said electric air heater.

### Claim 7 (depends on 1)

The system recited in claim 1, wherein said electric air heater generates between 1 kW and 30 kW of power.

### Claim 8

A method for outputting heated air at a controlled temperature and flow rate, comprising: an inlet and an outlet; providing a flow of air by means of an electric air blower; conducting the flow of air to an electric air heater including an electric resistance element upstream of the outlet; using a mass flow sensor connected upstream of an inlet of the electric air blower in a direction opposite the flow of air for generating a mass flow measurement signal MassFlow; generating an input temperature signal TempIN representing an input temperature; controlling electric power to said electric air heater in response to a first control signal; controlling mass flow through said electric air heater in response to a second control signal; and receiving the mass flow measurement signal MassFlow and the input temperature signal TempIN and providing a user input for inputting a temperature command signal TempCMD and a volume command signal VolumeCMD used by the controller for outputting air at a controlled temperature, calculating
TempCMD=TempIN+ΔT,
TempCMD=TempIN+((K×PowerIn/MassFlow)), and
PowerIn=(TempCMD−TempIN)×MassFlow/K, and
generating said first and second control signals as a function of the calculation, wherein the step of generating said inlet temperature signal TempIN is performed with a temperature sensor arranged at the input of said electric air heater.

### Claim 9 (depends on 8)

The method recited in claim 8, wherein the step of controlling mass flow through said electric air heater is performed with a controllable air valve or throttle positioned between an output of said electric air blower and the inlet of said electric air heater.