Electricity Producing Condensing Furnace

1
Electricity Producing Condensing Furnace

• A Senior Project by
• Jim Owens

Advisor Prof. Frank Wicks
2
Presentation Overview

• The Concept
• Background
• Furnace Components and Operation
• Expected Effective Efficiency
• The Control Panel
• Power Sensor
• Normal and Abnormal Off Condition
• Testing and Results
• Next Steps and Acknowledgements

3
Background
4
Background

• EPCF first conceived of during energy crisis of
  the 1970s
• Heating Systems are fundamentally wasteful
• high temperature combustion heat not converted to
  electrical or mechanical energy
• Substantial stack and chimney losses

5
Background

• First Idea
• Natural gas fueled heat pumps with a potential
  efficiency exceeding 100
• Knocked out of picture by highly efficient, cost
  effective condensing furnaces.
• New Idea
• Combine the heat recovery capability of the
  condensing furnace with co-generation
• Provides the additional benefit of converting
  roughly 20 of the high temperature heat into
  electricity, which is more valuable than heat and
  can be stored.

6
Potential Benefits

• Lower electric and gas bills
• If everyone converted to this type of furnace,
  the world energy requirement could be reduced by
  15, the equivalent of 100 or so Nuclear Power
  plants

7
Furnace
8
Furnace Components

• Propane fueled single-cylinder air cooled engine
• 230 V single phase induction motor/generator

9
Multi-Purpose Components

• EPCF Module
• Houses furnace and generator
• Single Controller
• Turns module on/off and provides safety features
• Induction Motor
• Starting motor and generator
• Shaft-Mounted Fans
• also circulate space air
• Spark Plug
• also furnace ignition

• Engine
• Drives generator and acts as a furnace combustion
  chamber
• Exhaust stroke purges combustion gas
• Electric Utility
• Controls voltage and speed
• Serves as virtual electric storage
• No equipment cost or maintenance for end user
• Max power produced during coldest season
• Relieves utility loads at peak periods

10
Thermal Loop

• Cold Side
• Cold air flows in though the secondary heat
  exchanger
• Carries heat away from the engine and motor
  (cooling them)
• Hot air is forced through the primary heat
  exchanger where it is heated further before
  flowing out to the house

• Hot Side
• Combustion gases are forced through the primary
  and secondary heat exchangers

11
Effective Efficiency
h95
I
Engine
Motor
II
h25
h80
Exhaust
IN 100
OUT 95 x 80 4 x 20 156
h OUT/IN 156 / 100
h156
12
Control Panel
13
Control Panel

• Components
• Power Meter
• Power Sensor
• Thermostat
• Fuses
• Transformer
• On/Off Relay
• Time Delay Relay
• Set/Reset Relay
• Power Sensor Relay
• Power and Fuel to Furnace Switch
• Solenoid

14
Modified Power Meter
Consuming Power

• CAD cell
• light sensitive switch
• conducts when light hits it
• Consuming Power
• Disc rotates CCW
• Light is blocked
• Producing Power
• Disc rotates CW
• Light shines through hole

CAD
Producing Power
CAD
15
Modified Power Meter
Load

• Two magnetic fields set up eddy currents on the
  disc
• 1 proportional to current
• 1 proportional to voltage
• They are situated adjacent to each other
• The rotational force on the disc is FROT
  (iv)cos q
• A change in the direction of power flow will
  cause the disc to rotate in the opposite direction

Disc
B a i
B a v
To Grid
B a v
B a i
F a iv
Hole
16
Control Panel Circuit
Control Panel Circuit
TIME DELAY INTERVAL ON
RESET
-

NO
NC
NO
NO
NO
THERMOSTAT
ON/OFF24 VAC
SET/RESET24 VDC
24 VAC
CAPACITOR
NO
MOTOR STARTER
FUEL SOLENOID
POWER SENSOR 24 VDC
-

CAD CELL
24 VAC
17
Normal Off
Normal Off
TIME DELAY INTERVAL ON
RESET
-

NO
NC
NO
NO
NO
THERMOSTAT
ON/OFF24 VAC
SET/RESET24 VDC
24 VAC
CAPACITOR
NO
MOTOR STARTER
FUEL SOLENOID
POWER SENSOR 24 VDC
-

24 VAC
CAD CELL
The SET/RESET Relay is always energized unless
the system shuts down due to failure
18
On (Initial Condition)Thermostat On
On (Initial Condition) Thermostat on
TIME DELAY INTERVAL ON
RESET
-

NO
NC
NO
NO
NO
THERMOSTAT
ON/OFF24 VAC
SET/RESET24 VDC
24 VAC
CAPACITOR
NO
MOTOR STARTER
FUEL SOLENOID
POWER SENSOR 24 VDC
-

24 VAC
CAD CELL
When the temperature of the house falls below the
set temperature, the thermostat closes. This
energizes the ON/OFF and TIME DELAY relays and
sends current to the POWER SENSOR relay.
19
On (Initial Condition)ON/OFF energized
On (Initial Condition) ON/OFF energized
TIME DELAY INTERVAL ON
RESET
-

NO
NC
NO
NO
NO
THERMOSTAT
ON/OFF24 VAC
SET/RESET24 VDC
ON/OFF24 VAC
24 VAC
CAPACITOR
NO
MOTOR STARTER
FUEL SOLENOID
POWER SENSOR 24 VDC
-

24 VAC
CAD CELL
The ON/OFF relay is energized, opening the
normally closed switch that sends current to the
SET/RESET relay. This relay will will remain
energized for about three seconds from the power
stored in the CAPACITOR.
20
On (Initial Condition)TD energized
On (Initial Condition) ON/OFF energized TD
energized
Furnace Operating
TIME DELAY INTERVAL ON
TIME DELAY INTERVAL ON
RESET
-

NO
NC
NO
NO
NO
THERMOSTAT
ON/OFF24 VAC
SET/RESET24 VDC
24 VAC
CAPACITOR
NO
MOTOR STARTER
FUEL SOLENOID
POWER SENSOR 24 VDC
-

24 VAC
CAD CELL
Simultaneously, the TIME DELAY relay coil is
energized. The normally open switch will close
and remain closed until some set time is reached.
Current now flows to the SET/RESET relay through
a different path. At this point, the motor
starter is activated and the solenoid is tripped,
starting the motor and sending fuel to the engine.
21
On (Initial Condition)POWER SENSOR
On (Initial Condition) ON/OFF energized TD
energized POWER SENSOR
TIME DELAY INTERVAL ON
RESET
-

NO
NC
NO
NO
NO
THERMOSTAT
ON/OFF24 VAC
SET/RESET24 VDC
24 VAC
CAPACITOR
NO
MOTOR STARTER
FUEL SOLENOID
POWER SENSOR 24 VDC
-

24 VAC
CAD CELL
The CAD CELL acts as a switch. It will only close
(conduct electricity) when light is striking it.
If the EPCF is producing power, the hole in the
the modified power meter dial will be oriented as
it is in the inset picture, allowing light to
reach the CAD CELL.
22
On (Overlap Condition)
On (Overlap Condition) ON/OFF energized TD
energized POWER SENSOR energized
Furnace Operating
TIME DELAY INTERVAL ON
RESET
-

NO
NC
NO
NO
NO
THERMOSTAT
ON/OFF24 VAC
SET/RESET24 VDC
24 VAC
CAPACITOR
NO
MOTOR STARTER
FUEL SOLENOID
POWER SENSOR 24 VDC
POWER SENSOR 24 VDC
-

24 VAC
CAD CELL
CAD CELL
When both the TIME DELAY and POWER SENSOR
switches are closed, there are two paths that the
current can flow through. This is called the
overlap condition
23
On (Final Condition)
On (Final Condition) ON/OFF energized TD
energized POWER SENSOR energized
Furnace Operating
TIME DELAY INTERVAL ON
RESET
-

NO
NC
NO
NO
NO
THERMOSTAT
ON/OFF24 VAC
SET/RESET24 VDC
24 VAC
CAPACITOR
NO
MOTOR STARTER
FUEL SOLENOID
POWER SENSOR 24 VDC
-

24 VAC
CAD CELL
After a set amount of time (approx. 30 sec), the
TIME DELAY relay will shut down.
24
Normal OffThermostat off
Normal Off
TIME DELAY INTERVAL ON
RESET
-

NO
NC
NO
NO
NO
THERMOSTAT
ON/OFF24 VAC
SET/RESET24 VDC
24 VAC
CAPACITOR
NO
MOTOR STARTER
FUEL SOLENOID
POWER SENSOR 24 VDC
-

24 VAC
CAD CELL
When the temperature inside the house rises above
the set temperature, the thermostat switch opens
and the system returns to normal off
25
Tripped OffThermostat On
Tripped Off Thermostat On
TIME DELAY INTERVAL ON
RESET
-

NO
NC
NO
NO
NO
THERMOSTAT
ON/OFF24 VAC
SET/RESET24 VDC
24 VAC
CAPACITOR
NO
MOTOR STARTER
FUEL SOLENOID
POWER SENSOR 24 VDC
-

24 VAC
CAD CELL
If the furnace fails to produce power at any time
after the TIME DELAY relay cuts out, then the
POWER SENSOR relay will de-energize, causing the
furnace to shut down
26
Tripped OffThermostat Off
Tripped Off Thermostat Off
TIME DELAY INTERVAL ON
RESET
-

NO
NC
NO
NO
NO
THERMOSTAT
ON/OFF24 VAC
SET/RESET24 VDC
24 VAC
CAPACITOR
NO
MOTOR STARTER
FUEL SOLENOID
POWER SENSOR 24 VDC
-

24 VAC
CAD CELL
In order to turn the furnace back on, the owner
would have to go to the furnace and push the
reset button.
27
Control Panel Logic Table
Component States
Output State
Thermostat On/Off
Time Delay
Power Sensor
Set/ Reset
Reset Button
MODE
On (Initial Condition)
1
1
1
0
0
1
On (Overlap Condition)
1
1
0
1
1
1
On (Final Condition)
1
0
0
1
1
1
Normal Off
0
1
0
0
0
0
Tripped off/ Thermostat On
0
1
0
0
0
0
Tripped off/ Thermostat Off
0
0
0
0
0
0
Reset/ Thermostat Off
0
1
0
0
1
0
Reset/ Thermostat On (Initial Condition)
1
1
1
0
1
1
Attempted Reset/ Ther- mostat On (Final Period)
1
0
0
0
1
0
1 On 0 Off
28
Overview
Propane Tank
Power Meter
Modified Power Meter
Fuses
Hot
Hot
230 V
Neutral
230 V
Switch
120 V
Solenoid
Transformer
24 V
Control Panel
Air in
Furnace Module
Fuel
Air out
Exhaust
29
Testing and Results
30
Thermocouple Placement
Primary HX
Engine
Motor
Secondary HX
Fuel In
Electricity In/Out
Exhaust

6. Engine Fin
0. Ambient
1. Exhaust pipe near engine
7. Motor Fin
2. Exhaust pipe into Primary HX
8. Inside Box temperature (bottom of
outgoing air duct)
3. Exhaust pipe out of Primary HX
4. Exhaust pipe into Secondary HX
9. Outgoing air temperature
5. Exhaust gas out
10. Intake air temperature
31
Data Acquisition
32
Performance Testing
33
Results
Heat Loss (through box)
Fuel
Electricity
Heat Recovered
69,377
10,235
9,524
?


Heat Recovered 49,618
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Results
Determine mass of combustion gas from
Stoichiometry
C3H8 5(02 3.76N2) 3CO2 4H2O
5(3.76)N2
1 lbm of propane requires 15.6 lbm of air,
therefore, for 3.5 lbm fuel, mass of combustion
gas 58.1 lbm
35
Results
Primary Heat Exchanger
Secondary Heat Exchanger
QPHX (mcpDT)gases
Q2HX (mcpDT)gases
QPHX 7155 Btu/hr
Q2HX 3238 Btu/hr
Efficiency
130


36
Results
37
What Went Wrong?

• Air leakage from box
• Heat loss through uninsulated box
• More space air circulation is required
• Shaft mounted cooling fans are not sufficient

38
Next Steps

• Rebuild box
• better material
• Noise/Vibration
• 2 cylinder engine
• Solid State Control Panel

• Catalytic Converter
• Oxygen sensor in exhaust gas
• Optimize fuel mixture
• CO Detector
• Increase circulation

Conduct sustained testing for an entire heating
season
39
Acknowledgements

• Prof. Wicks
• Stan Gorski
• Machine Shop
• Physical Plant

40
Questions?