Capture of Heat Energy From Diesel Engine After Cooler Circuit (2006 Annual Report) Mark Teitzel Alaska Village Energy Corporation 907-565-5337 [email protected].

Capture of Heat Energy From

Diesel Engine After Cooler Circuit (2006 Annual Report)

Mark Teitzel

Alaska Village Energy Corporation

907-565-5337

[email protected]

Chuen-Sen Lin

University of Alaska Fairbanks

907-474-5126

[email protected]

Milestones

Design: Completion of exhaust heat recovery system design and an instrumentation plan.

Instrumentation and installation: Completion of installation of exhaust heat recovery system. Completion of instrumentation and calibration.

Testing and analysis: Exhaust condensate test and ph testExhaust heat recovery system performance test result for three different applications.

Demonstration: Meetings and communication between AVEC and UAF.

Heat Recovery System

Three Application Cases

Future cogeneration market segments (Alaska Energy Plan- Cogeneration chapter)

Building with low temperature baseboard heating Building with in floor radiant heating Community water loop temperature maintenance

o Residential micro cogeneration units (e.g. Stirling)o School cogeneration units (e.g. Diesel Generator)

Line Diagram

Heat Exchanger

Unit Heater

1102 - 13

1102 - 08

1102 - 17

1102 - 18

1102 - 20

1102 - 19

1102 - 14

1102 - 15

T1

T2

T3

mc

T6

T5

T4

T 7 T8

mu

mb

Pump

Flow Meter

Mass flow meterSCXI 1120

Before 3-way valve Temp20

After 3-way valve Temp19

Bypass Temp18

Before bypass Temp17

Exhaust15

Heat exchanger outlet Temp14

Heat exchanger inlet Temp13

Shell outlet 8

Name in DAQSlot in SCXI 1102

Measured Result of Three Applications(Rated load: 125 kW)

HX inlet temp 76.7C (170F) HX inlet temp 43.3C

(110F) No temp control

Parameters 50% Load

75% Load

100% Load

50% Load

75% Load

100% Load

50% Load

100% Load

Total coolant flow rate (kg/s) 1.49 1.45 1.37 1.31 1.25 1.26 1.24 1.26 HX coolant inlet temperature (deg C) 76.1 76.8 75.9 44.0 54.7 61.7 37.0 61.3 HX coolant outlet temperature (deg C) 81.1 84.8 87.6 49.8 64.6 74.6 43.4 74.2 Heat recovered by coolant (KW) 28.1 43.7 60.2 28.0 46.4 60.7 30.2 61.2

Exhaust flow rate (kg/s) 0.16 0.20 0.25 0.16 0.20 0.25 0.16 0.25 HX exhaust inlet temperature (deg C) 355.6 452.7 513.3 366.8 453.5 498.5 359.0 508.7 HX exhaust outlet temperature (deg C) 127.6 166.4 202.6 120.1 165.4 196.9 123.0 215.7

Exhaust heat release (KW) 38.2 61.5 83.1 43.1 62.2 80.3 40.1 78.9

HX efficiency (%) 74 71 72 65 75 76 75 78

Heat Recovered

Heat Recovered

0

10

20

30

40

50

60

70

50 75 100

% Load

Hea

t R

eco

vere

d (

kW)

Application 1

Application 2

Application 3

Efficiencies of the Three Applications

Efficiency

55

60

65

70

75

80

50 75 100

Load (%)

Eff

icie

ncy

(%

)

application 1

Application 2

Application 3

Discussion of Data Heat recovery system has worked as expected (consistent

performance).

Temperature control valve has worked as expected. Circuit setters effectively controlled the flow rates and pressure

drops.

According to engine performance data (before and after the installation of the system), the system showed no noticeable influence on engine performance (e.g. P, T).

According to the experimental data of the last 100 hours of engine operation, the performance of heat exchanger was consistent (e.g. Q, T).

Discussion of Data (continued)

The temperatures at various locations of the shell (i.e. exhaust) side of the heat exchanger (including exhaust outlet temperature) were much higher than the dew point (40C) for all operation conditions.

Coolant flow rate was lower than expected (24 gpm versus 30 gpm). What would be the effect on heat recovery?

Heat exchanger efficiencies at different loads were between 71% to 78%, which were lower than expected. According to the insulation of the shell of the heat exchanger (4-in Kaowool), the heat loss to the environment from the exhaust should be about 1/3 of the current heat loss (15 kW). (Double check: [1] homemade insulation to the connection pipes. [2] the measurement instrument and procedure)

Discussion of Data (Continue)

For the first type of heat recovery application, the inlet coolant temperatures of the HX for all three loads were controlled to the desired value (around 76C).

For the second application, the inlet coolant temperatures of HX could not be controlled to the desired temperature (around 43C) except for the case of 50% load (or lower load). Reason: the load simulator (i.e. the unit heat) did not have enough surface area. This problem can be solved by increasing the load capacity of the load simulator.

Engine Performance Data at 50 –hr and 100-hr

Engine Hours

Exhaust Temp (C)

Turbocharger Temp (C)

Fuel Consumption (L/hr.)

Before HX Installed

542 122 34

50 Hours After

540 142 34

100 Hours After

533 140 34

Fouling Resistance(Experimental data quoted from Grillot’s Paper)

Four different experimental cases

Total soot injected for about 25 hours for each case

Result:

Cases

(HX oil temp

Gas flow vel.)

Total mass injected (kg)

HX deposit mass (g)

Time to reach asymptotic fouling resistance (Hour)

Asymptotic fouling resistance (m^2 K/W)

100C, 8m/sec 4.91 65.15 11 0.043

200C, 8m/sec 5.73 54.29 8 0.032

100C, 4m/sec 5.15 96.63 44 0.104

200C, 4m/sec 3.97 81.17 23 0.077

Effect of Coolant Flow Rate on Heat Recovery

Heat recovered versus Flow Rate (Reference Flow Rate= 1.37 kg/s)

58.5

59

59.5

60

60.5

61

61.5

62

25 50 80 100 120 150

Flow rate (% of rated flow rate)

Hea

t R

eco

vere

d (

kW)

Heat recovered

Effect of Coolant Inlet Temperature on Heat Recovery

Effect of Coolant Temperature on Heat Recovery

54

56

58

60

62

64

66

68

70

72

74

15 35 55 65 76.7 85

Coolant Inlet Temperature (C)

Hea

t R

eco

vere

d

Effect of Surface Area on Heat Recovery

Effect of Surface Area on Heat Recovery(Reference area= 8 m^2)

0

10

20

30

40

50

60

70

80

25 50 100 150 200 300 400

Heat Exchanger Surface Area (%)

Hea

t R

eco

vere

d (

kW)

Modified Performance of the Three Different Application Cases (with enough simulation load)

76.7 C (170 F) Inlet to heat exchanger

54.4 C (130 F) Inlet to heat exchanger

15.6 C (60 F) Inlet to HX

Parameters 50% Load

75% Load

100% Load

50% Load

75% Load

100% Load

50% Load

100% Load

Total coolant flow rate (kg/s) 1.49 1.45 1.37 1.31 1.25 1.26 1.24 1.26 HX coolant inlet temperature (deg C) 76.7 76.7 76.7 54.4 54.4 54.4 15.6 15.6 HX coolant outlet temperature (deg C) 81.7 84.7 88.1 60.0 64.6 67.8 42.8 29.8

Heat recovered by coolant (KW) 28.0 43.7 61.3 27.1 47.9 62.9 32.2 67.4

Exhaust flow rate (kg/s) 0.16 0.20 0.25 0.16 0.20 0.25 0.16 0.25 HX exhaust inlet temperature (deg C) 355.6 452.7 513.3 366.8 453.5 498.5 359.0 508.7 HX exhaust outlet temperature (deg C) 128.1 166.3 203.8 128.0 155.9 185.7 107.0 185.7

Exhaust heat release (KW) 38.11 61.5 82.8 41.7 64.2 83.3 42.8 87.0

Percentage Difference in Heat Recovery Between Modified Case and the Original Case

Percentage Difference in Heat Recovery(Estimated HR of modified case - Measured HR)/Measured HR

-4

-2

0

2

4

6

8

10

12

% Load (%)

% D

iffe

ren

ce in

Hea

t R

eco

very

(%

)

Application 2

Application 3

Application 2 -3.214285714 3.232758621 3.624382208

Application 3 6.622516556 10.13071895

50 75 100

Heating fuel savings

76.7 C (170 F) Inlet to heat exchanger

54.4 C (130 F) Inlet to heat exchanger

15.6 C (60 F) Inlet to HX

Parameters (Full load: 125 kW)

50% Load

75% Load

100% Load

50% Load

75% Load

100% Load

50% Load

100% Load

Heat released by exhaust (kW) 38.1 61.5 82.8 41.7 64.2 83.3 42.8 87.0

Heat recovered by coolant (kW) 28.0 43.7 61.3 27.1 47.9 62.9 32.2 67.4 Heating fuel saved per 100 kW-hr of electrical power (gal)

1.10

1.14

1.20

1.06

1.25 1.23 1.26 1.32 Heating fuel cost saved per 100 kW-hr electrical power ($2.5/gal)

2.75

2.86

3.00

2.66

3.13 3.09 3.16 3.31

Heating Fuel Saving per 100 kW-hr of electric Power

0

0.2

0.4

0.6

0.8

1

1.2

1.4

50 75 100

% Load

He

atin

g F

ue

l S

av

ing

(G

allo

n)

Application 1

Application 2

Application 3

Conclusion Completion of design installation and instrumentation of the exhaust

heat recovery system.

Study of the system performance:

Control components (e.g. valve controller and circuit setters) worked as expected.

System performance data indicated that HX system had no noticeable effect on engine performance.

Based on HX performance data, soot thermal resistance has not changed much during the last 50 hours operation (need further investigation)

Conclusion (continue)Heating fuel saving per unit kW-hour for higher load was better but not critical.

A relatively large amount of heat (compared to calculated result) dissipated into the surrounding. (Needs further investigation)

According to measured temperature distribution of the shell side, corrosion may not become a problem for this exhaust HX.

Lower coolant flow rate (24 gpm versus 30 gpm) may not affect the heat recovery rate significant (less than 1%).

To lower the requirement of coolant inlet temperature will moderately increase the heat recovery rate. (Application 1 has the lowest heat recovery and application 3 has the highest).

Current Work

To continue performance data collection to further confirm the conclusion listed previously.

To develop a preliminary tool for heat exchanger system cost analysis. (Parameters: size, pressure drop, flow rate, capital and operation cost, etc.).

To propose some recommendations for exhaust heat exchanger design.

To continue collect data and conduct economic analysis.

Future work

Select a turbocharger compressed air heat exchanger and install the turbocharger after cooler heat exchanger system.

Conduct performance and economic analysis for the turbocharger heat recovery system.

Select a village as demonstration site for turbocharger after cooler heat recovery system field demonstration.

Acknowledgement

DOE AETDL AVEC ICRC

Questions ?