Trane UH-PRC001-EN manual Correction Factors for Propylene Glycol/Water, Selection Procedure, Step

Page 20
Correction Factors for Propylene Glycol/Water

Selection Procedure

Step 4.

Determine the pressure drop at 6.53 GPM. Pressure drops are cataloged for both standard wall (SWT) and heavy wall. (HWT) tube coils. In this example, if a SWT coil is selected the pressure drop, by interpolation is 2.38 feet of water.

Step 5.

Calculate the final air temperature

F.T. = E.A.T. +

Btu/hr

CFM x 1.085

 

= 70 + 96000 = 70 + 53.2 = 123.2° 1661 x 1.085

Example 2

Determine the capacity of a Model 336P unit heater operating at 180° (EWT), 100° (EAT) and 15° (WTD).

Step 1.

Find conversion factor (inTable SP-11) = 0.546

Step 2.

Adjust the water temperature drop

Adj. WTD = 15 = 27.5°

.546

Step 3.

Multiply the MBH (interpolated) at

27.5° WTD, 200° EWT and 60° EAT by the factor to obtain the MBH at desired conditions.

0.546 x 224.9 = 123.0 MBH

Step 4.

WTD = 27.5 x 0.546 = 15°

Step 5.

GPM =

Btu/hr

= 123,000 = 16.9

485xWTD

 

(485)(15)

Step 6.

Pressure drop interpolated at 27.5°WTD for a SWT coil is 1.82 feet of water.

Step 7.

Calculate final temperature

F.T. = E.A.T. +

 

Btu/hr

 

CFM x 1.085

 

= 100° +

 

 

 

123,000

= 121.8°

 

5210 x 1.085

Note:

If a constant water temperature drop is desired, apply the conversion factor to the WTD and to the desired MBH and enter 200° EWT column at these conditions. Select the unit which will provide the equivalent MBH at the adjusted WTD. The GPM can then be interpolated from the table at the adjusted WTD. To determine the actual capacity at operating conditions proceed as outlined in example #2.

If a constant GPM is desired, enter the 200° EWT column at the given or calculated GPM. Select the unit which will provide the equivalent MBH at this GPM. To determine the actual capacity at operating conditions in this case proceed as outlined in example #1.

Table SP-11 – Unit Heater HotWater Conversion Factors (AppliesToTables PD-1 - PD-5)

Ent.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Air

 

 

 

 

 

 

 

 

 

 

 

 

Entering WaterTemperature

 

 

 

 

 

 

 

 

Temp.

 

160

170

180

190

200

210

220

230

240

250

260

270

280

290

300

310

320

330

340

350

360

370

380

390

400

30

.962

1.036

1.110

1.182

1.259

1.331

1.408

1.482

1.554

1.627

1.702

1.780

1.850

1.925

2.000

2.070

2.142

2.220

2.295

2.370

2.440

2.515

2.590

2.660

2.735

40

.880

.954 1.024 1.100 1.171 1.249

1.318 1.391 1.468

1.539

1.612 1.686

1.759

1.831

1.909

1.976

2.048

2.120 2.193

2.268 2.348

2.417

2.488 2.560 2.632

50

.795

.869

.940

1.011

1.085

1.158

1.230

1.301

1.374

1.448

1.520

1.590

1.664

1.735

1.809

1.882

1.953

2.024

2.095

2.168

2.242

2.312

2.388

2.459

2.530

60

.715

.785

.859

.929 1.000 1.071

1.141 1.215 1.285

1.359

1.429

1.500

1.571

1.642

1.715

1.785

1.858

1.930 2.000

2.070 2.140 2.215 2.285 2.360 2.430

70

.634

.704

.774

.845

.917

.988 1.058 1.129 1.200

1.270

1.340

1.410

1.482

1.552

1.622

1.694

1.764

1.838 1.907 1.976 2.045 2.116 2.188 2.258 2.332

80

.568

.628

.698

.768

.838

.908

.978

1.048

1.118

1.188

1.258

1.328

1.398

1.468

1.538

1.604

1.674

1.742

1.815

1.884

1.952

2.020

2.091

2.162

2.230

90

.484

.552

.622

.690

.760

.829

.898

.967 1.036 1.106 1.173

1.244

1.311

1.380

1.450

1.515

1.585

1.655

1.723

1.795

1.862

1.930

1.998

2.067

2.137

100

.410

.478

.546

.615

.684

.753

.820

.889

.957

1.025

1.095

1.161

1.230

1.300

1.368

1.433

1.499

1.569

1.638

1.705

1.776

1.843

1.910

1.977

2.046

Apply to the 200 F entering water capacities only.

Correction Factors for Propylene Glycol/Water

When sizing equipment for systems that will utilize a propylene glycol solution, consider the following factors:

1.Heat transfer @180F with no increase in flow rate

Propylene

Glycol

20% solution

.97*

50% solution

.90*

Table SP-12 –Trane Unit Heater Nomenclature (AppliesToTables PD-1 - PD-5)

Abbreviations

Definitions

MBH

1000 BTU Per Hour

GPM

Gallons Per Minute

FT

FinalTemperature °F

PD-S.W.T.

Feet Of Water Pressure Drop - Standard WallTubes.

PD-H.W.T

Feet Of Water Pressure Drop - Heavy WallTubes

 

Propylene

 

Propylene

2. GPM required @180F,

Glycol

 

 

Glycol

20°D (no correction to

 

 

 

 

pump curve)

1.10%

7. pH@50% by volume.

9.5

3. Pump head required

 

8. Freezing Point

55% by volume —

@180F w/increase in

 

 

50%

-28F

GPM

1.23%*

 

40%

-13F

4. Specific gravity

 

 

30%

+28F

 

 

20%

+17F

(water = 1.0)

1.045-1.055*

**Compared to water

 

 

 

 

 

 

5. Pounds/Gallons@60F

 

 

 

 

(water = 8.3453

 

 

 

 

Pounds/Gallons)

8.77

 

 

 

20

UH-PRC001-EN

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