DAQ Calibration for Heat Exchanger

Calibration of Cold/Hot Flow Rateand Temperature

UTCENCH/ENEV 435

11/25/03

Greg Kirton

Kevin Zitzow

Phuong Mai

Objectives

Calibrate Cold Water Flow Rates from DAQ with Measured Flow Rates

Calibrate Hot Water Flow Rates from DAQ with Measured Flow Rates

Calibrate Temperatures from DAQ with Measured Temperatures

Heat Exchanger in UTC Lab

FT=Flow Transmitter

S=Solenoid

TT= Temp Transmitter

CW=Cold Water

W/H=Water Heater

CWS=Cold Water Supply

CWR=Cold Water Return

Schematic of Heat Exchanger

Procedure for Measurements

A stopwatch was used to keep time A 1000 ml graduated cylinder was used to measure

volume Measured volume of water obtained in 10 seconds. Varied

% Opening of Cooling Water Valve % Hot Water Pump Speed

4 measurements were made for each setting

Data Analysis

Measurements were averaged and error was calculated using student’s T equation.

http://chem.engr.utc.edu/engr329/Lab-manual/Students-T.htm

Computer DAQ was averaged and standard deviation was calculated in Excel DAQ error was reported as 2xSTDEV

Cold Water Flow Calibration

Cold Water Flow Data

0

2

4

6

8

10

12

14

0 20 40 60 80 100

% Valve Open

Flo

w R

ate

(lb

/min

)

Data from DAQ

Measured Data

Cold Water Flow Rate Calibration

y = 1.4981x + 0.1922

R2 = 0.9944

0

2

4

6

8

10

12

0 2 4 6 8 10 12

DAQ Flow rate (lb/min)

Mea

sure

d Fl

ow R

ate

(lb/m

in)

Hot Water Flow Calibration

Hot Water Flow Data

0

2

4

6

8

10

0 20 40 60 80 100

% Pump Speed

Flo

wra

te (l

b/m

in)

Measured Data

DAQ

Hot Water Flow Rate Calibration

y = 0.0255x2 + 1.2302x - 2.2253

R2 = 0.9942

0

2

4

6

8

10

0 2 4 6 8 10

DAQ (lb/min)

Mea

sure

d (lb

/min

)

Temperature Calibration

Insulation

Tube Side Port B

Tube Side Port A

Shell Side Port B

Shell Side Port A

Temperature Data

Location Measured (oC) DAQ (oC)CWS From Lab Sink 22.5 21RTD Shell Side Port A 46 47RTD Shell Side Port B 31.5 31RTD Tube Side Port A 30.8 31.7RTD Tube Side Port B 17.7 16.7

Overall Heat Transfer Coefficient of Heat Exchanger

Objectives

Compare total heat transfer rates of the hot and cold streams.

Determine the overall heat transfer coefficient.

Pictures of the Heat Exchanger

Hot water in

Cold water in

Tube bundle

Heat Transfer Properties

55 tubes Tube Volume = 143 cc Tube Length = 506 mm Total heat transfer area = 0.27 m2

Heat Transfer Diagram

Thot,inThot,out

Tcold,in Tcold,out

q

lmTUAq

Log Mean Temperature

))(

)(ln(

)()(

)/ln(

,,

,,

,,,,

12

12

ocih

icoh

ocihicohlm

TT

TT

TTTT

TT

TTT

Heat Transfer Rate Equations

)(

)(

,,,

,,,

ihohchhh

icoccpcc

TTcmq

TTcmq

1st Run

Input = 75% Hot water mass flow rate (HWS) of

0.4124kg/s

CW valve open = 60 % Cold Water mass flow rate (CWS) of 0.080kg/s

q and U Results of 1st Run

qc =5.76 kW

qh = 3.37 kW

Uc = 1352 W/m2K

Uh= 792 W/m2K

2nd Run

Input = 40% Hot water mass flow rate (HWS) of 0.0258 kg/s

CW valve open = 40 % Cold water mass flow rate (HWS) of 0.0505

kg/s

q and U Results of 2nd Run

qc =2.33 kW

qh = 2.25 kW

Uc = 532 W/m2K

Uh= 514 W/m2K

Overall Heat Transfer Coefficient (U)

0

200

400

600

800

1000

1200

1400

1

U (W

/m2 K)

1). HWS = 0.04124kg/s and CWS = 0.080 kg/s2). HWS = 0.0258 kg/s and CWS = 0.0505 kg/s

1st

2nd

1st

2nd

Hot FlowCold Flow

Total Heat Transfer Rate (q)

0

1

2

3

4

5

6

7

1

q(kW

) Hot Flow Cold Flow

1st

2nd 2nd

1st

1). HWS = 0.04124kg/s and CWS = 0.080 kg/s2). HWS = 0.0258 kg/s and CWS = 0.0505 kg/s

Conclusions

1st run: qc and qh are not closed.

2nd run: qc and qh are closed.

1st run: Uc and Uh are not closed.

1st run: Uc and Uh are closed.

U increases as HWS and CWS increase.1). HWS = 0.04124kg/s and CWS = 0.080 kg/s2). HWS = 0.0258 kg/s and CWS = 0.0505 kg/s

Questions

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