TO OBSOLETE .1

1990 TCP

STANDARD for V

CENTRIFUGAL OR • V

ROTARY SCREW •

V WATER-CHILLING

PACKAGES

•

__________

i Standard 550-90

AIR-CONDITIONING

____________________

& REFRIGERATION

INSTITUTE

i

I t• U

1501 WILSON BOULEVARD • ARLINGTON, VIRGINIA 22209
IMPORTANT

SAFETY RECOMMENDATION

It is strongly recommended that the product be designed, constructed, assem

bled and installed in accordance with nationally recognized safety require

ments appropriate for products covered by this standard.

ARI, as a manufacturers’ trade association, uses its best efforts to develop

standards, employing state-of-the-art and accepted industry practices. Iow

ever, A does not certify or guarantee safety of any products, components

or systems designed, tested, rated, installed or operated in accordance with

these standards or that any tests conducted under its standards will be nonhazardous or free from risk.

I

I

ARI CERTIFICATION PROGRAM PROVISIONS

Scope of the Certification Program

All water-cooled centrifugal and rotary screw water-chilling packages rated below

1600 tons at ARI Standard Rating Conditions, of the hermetic and open type.

electric motor driven 60 Hz below 5000 volts, as covered by this standard, are

included in the Certification Program. Included are chillers with single bundle shells

(single water circuits or multiple condensers on a single water circuit are included).

It is recognized that more than one condenser can be used on a single water circuit

on a chiller.

Certified Ratings

The Certification Program ratings verified by test are:

I. Capacities (ton) [kW],

2. Power Inputs per Ton (kW/ton) [kW/kW],

3. Water Pressure Drops (see Section 5.1.8) (psi or feet of water) [kPaJ, all of the

above at standard ratings conditions (see Section 5.1.1) and at application ratings

conditions (see Section 5.1.2) for both full and part loads (see Section 5.1.6 for

part load performance requirements),

4. Integrated Part Load Values (IPLV’s) (see Section 5.1.6), and

5. Application Part Load Values (APLV’s) (see Section 5.1.6).

NOTE:

This standard supersedes ARI Standard 550-88

Price $22.00 © COPYRIGH1 1990, by Air-Conditioning and Refrigeration Institute

Printed in U.S.A. ‘%i Registered United States Patent and Trademark Office
SECTION

Section 1.

Section 2.

Section 3.

Section 4.

Section 5.

Section 6.

Section 7.

Table 1. Part Load Conditions for Rating

Figure 1. Allowable Tolerance Curves for Full and Part Load

Figure 2. IPLV and APLV Tolerance Curve /

APPENDIX A

STANDARD REQUIREMENTS FOR TESTING CENTRIFUGAL

OR ROTARY SCREW WATER-CHILLING PACKAGES

APPENDIX B

METhOD AND EXAMPLE OF CALCULATING INTEGRATED PART

- LOAD VALUE

I

I

2

2

6

6.

4

6

7

Section Bi. Purpose 13

Section B2. Scope 13

Section B3. Equation and Definition of Terms 13

Section B4. Example Calculations 14

Figure Bi. Example Part Load Factor Curve 15

O?ERTY F II S GOVERNMEIT

‘ ,41P

4

V

)

OBSOLETE

TABLE OF CONTENTS

PAGE

r

Purpose

Scope

Definitions

Standard Equipment

Published Rating Requirements

Refrigerant Designation

Voluntary Conformance

Section Al.

Section A2.

Section A3.

Section A4.

Section AS.

Section A6.

Section A7.

Section A8.

Purpose 8

Scope 8

Definitions 8

Test Methods 8

Instruments 8

.Measurements 9

Test Procedure 10

Calculation of Results 12
ARI STANDARD 550-90

CENTRIFUGAL OR ROTARY SCREW WATER-CHILLING PACKAGES

Section 1. Purpose

1.1 Purpose. The purpose of this standard is to estab

lish, for centrifugal or rotary screw water-chilling pack

ages: definitions and nomenclature; a description of

what constitutes such a package; published rating con

ditions; standard requirements for testing and a basis

for published ratings; and proper refrigerant designa

tion in systems.

1.1.1 This standard is intended for guidance of the

industry, including specifying agencies, manufac

turers, installers, contractors and users.

1.2 This standard is subject to review and amendment

as the technology advances.

Section 2. Scope

2.1 Scope. This standard applies to centrifugal or ±0-

tary screw water-chilling packages as defined in 3.2.

2.1.1 This standard applies to both hermetic and

open centrifugal or rotary screw water-chilling

packages which have continuous capacity modula

tion, whether driven by an electric motor, steam

turbine or other prime mover.

2.1.2 This standard does not include sanitary pro

visions necessary for the handling of potable Iiq

uids.

Section 3. Definitions

3.1 Definitions in ASHRAE “Terminology of Heating,

Ventilation, Air-Conditioning and Refrigeration” apply

except as indicated by the definitions following in this

section.

3.2 Centrifugal or Rotary Screw Water-Chilling Package.

A Factory-designed and prefabricated assembly (not

necessarily shipped as one package) of one or more

compressors, condensers, and water coolers, with inter

connections and accessories.

3.2.1 An open centrifugal or rotary screw compres

sor is defined as having a shaft or other moving part

extending through a casing to be driven by an out

side source of power, thus requiring a stuffing box,

shaft seal, or equivalent, between a fixed and a

moving part.

3.2.2 A hermetic centrifugal or rotary screw com

pressor is defined as consisting of a compressor with

its prime mover and drive, all ofwhich are enclosed

as to operate in the refrigerant atmosphere.

3.2.3 A purge is a device for removing non-con

densable gas and moisture from refrigerant con

densers.

3.2.4 A pump-out system is a system which facili

tates transfer of refrigerant from one heat exchan

ger to another or to or from a storage vessel.

3.3 Fouling Factor. The thermal resistance due to foul

ing accumulated on the heat transfer surface.

3.3.1 Field Fouling Allowance. Provision for antic

ipated fouling during use specified in hr sq ft F/Btu

[m2 °CIWJ.

3.4 Integrated Part Load Value (IPLV). A single num

ber part-load efficiency figure of merit calculated per

the method described in 5.1.7 referenced to Standard

Rating Conditions (See Table 1).

3.5 Application Part Load Value (APLV). A single

number part-load efficiency figure of merit calculated

per the method described in 5.1.7 referenced to Se

lected Application Rating Conditions (See Table 1).

3.6 Published Rating. A statement in the form of cat

alogs or computer output, of the assigned values of

those performance characteristics, under stated rating

conditions, by which a Unit may be chosen to fit its

application. These values apply to all units of like nom

inalsize and type (identification) produced by the same

manufacturer.

3.6.1 A Standard Rating is a rating at Standard

Rating Conditions based on test data.

3.6.2 An application rating is a. rating at applica

tion rating conditions (other than Standard Rating

Conditions).

3.6.3 Selected Application Rating is a rating devel

oped at specific application conditions.

3.7 Manufacturer. The manufacturer of the water-chill

ing package unless otherwise stated.

3.8 “Shall”, “Should”, or “It Is Recommended” shall

be interpreted as follows:

3.8.1 Shall. Where “shall” is used for a provision

specified, that provision is mandatory if compli

ance with the standard is claimed.

1
ARI STANDARD 550-90_

3.8.2 Should or It Is Recommended. “Should” or

“it is recommended” is used to indicate provisions

which are not mandatory hut which are desirable

as good practice.

Section 4. Standard Equipment

4.1 A centrifugal or rotary screw water-chilling pack

age shall include the following standard equipment:

I. Compressor and drive assembly consisting of one

or more centrifugal or rotary screw single or multi

stage compressor(s) with necessary lubrication

system(s).

a. Hermetic drive: Prime mover, with gears and

couplings as necessary integral with the com

pressor.

b. Open drive: Prime mayer, with gears and cou

plings as necessary (except when furnished by

others).

2. Refrigerant condenser: A refrigerant-to-water,

refrigerant-to-air or evaporatively cooled heat ex

changer. Refrigerant-to-water condensers shall

have a water side suitable for a working pressure

of 150 psig [1034 kPa] or more.

3. Cooler (refrigerant evaporator): A refrigerant-towater heat exchanger; with water side suitable for

a working pressure of 150 psig [1034 kPa] or more.

4. Controls as necessary to regulate package capacity

and meet applicable safety requirements specified

by others.

Section 5. Published Rating Requirements

5.1 Published Ratings. Published ratings consist of

Standard Ratings and application ratings, whether pub

lished in catalogs or as computer output.

5.1.1 &andard Rating C’ondirions. Standard Rat

ings shall be determined at Standard Rating Con

ditions, as follows:

Cooler (All Condenser Types)

Leaving chilled water

temperature 44 F [6.7°C]

Cooler water-side field fouling

allowance 0.00025 hr sq ft F/Btu

[0.000044m 2. °CIW]

Cooler refrigerant-side fouling

factor allowance 0.0000 hr sq ft FIBtu

10.0000 m2• °C/W]

Chilled water flow rate 2.4 gpmlton

1 0.043 Us per kw]

Con denser (Water-cooled)

Entering condenser water

temperature 85 F [29.4°C]

Condenser water-side field fouling

allowance 0.00025 hr sq ft F/Btu

[0.000044 m2 °C/WJ

Condenser refrigerant-side fouling factor

allowance 0.0000 hr sq ft F/Btu

[0.0000 m2 °C/W]

Condenser water flow rate 3.0 gpm/ton

[0.054 L/s for each kW capacity]

Condenser (A jr-cooled)

Air entering

condenser 95 F [35.0°C] dry bulb

Condenser refrigerant-side fouling factor

allowance 0.0000 hr sq ft F!Btu

[0.0000 m2 °C/W]

Condenser air-side fouling factor

allowance 0.0000

Barometric Pressure ... 29.92 in. Hg [101 kPa]

Con denser (Evaporatively-cooled)

Air entering

condenser 75 F [23.9°C] wet-bulb

Condenser refrigerant-side fouling factor

allowance 0.0000 hr sq ft F/Btu

[0.0000 m2 °C/Wj

Condenser air-side field fouling

allowance 0.00000 hr sq ft F/Btu

[0. 0000 m2

Barometric

Pressure 29.92 in. Hg [101 kPa]

5.1.2 Application Rating Conditions. It is recom

mended that application ratings (at other than

Standard Rating Conditions) include ratings at the

following range of conditions:

All Condenser Types

Leaving chilled water temperature 40-48 F

[4.4 to 8.9°C]

increments 2 F or less .. [1°C or less]

Condenser (Water-cooled),

Entering condenser water

temperature 80-95 F [26.7 to 32.2°C]

in increments 5 F or less [3°C or less]

Condenser (Air-cooled)

Entering air temperature to the

condenser 85-115 F [29.4 to 46.1°C]

dry bulb

in increments 10 F or less [6°C or less]

.
ARI STANDARD 550-90

Condenser (Evaporatively-cooled)

Entering air temperature to

condenser 70-80 F [21.1 to 26.7°C]

wet bulb

in increments 2.5 F or less .... [1.5°C or less]

5.1.2.1 Field Fouling Allowances. When appli

cation ratings are published, they shall include

those with field fouling allowances as specified

in 5.1.1. Additional application ratings, or

means of determining these ratings, at other field

fouling allowances may also be published (See

5.2).

5.1.3 Determination of Ratings. Published ratings

shall be determined from test results in accordance

with the following:

a. Cooler and condenser water-side heat trans

fer surfaces shall be considered clean during

testing. Tests will be assumed to reflect a

fouling factor of 0.000 hr sq ft F/Btu [0.0000

m2 °C/W].

b. To determine published ratings at any field

fouling allowance from test data at a fouling

factor of 0.000 hr sq F/Btu [0.0000 m2

W], the calculations for fouling adjustment

described in ARI Standard 450 for WaterCooled Refrigerant Condensers, Remote Type

and ARI Standard 480 for RefrigerantCooled Liquid Coolers, Remote Type shall be

used.

5.1.4 Net Tons. The published tons of refrigera

tion [kW] are considered as net usable tons [kWj

to the customer’s system.

5.1.5 Power Input. Published power input require

ments shall be the power required from the cus

tomer’s power source and shall include the average

power required by all components of the package

including the purge, oil pumps, oil heaters, motor

starters, frequency converters and controls fur

nished by the manufacturer. Power required by

water pumps shall be excluded.

5.1.6 Part Load Performance. Part load perfor

mance of a centrifugal or rotary water-chilling

package, may be presented in three ways:

a. Integrated Part Load Value (IPLV) which is

based on Standard Rating Conditions (See

Table 1).

b. Application Part Load Value (APLV) which

is based on a Selected Application Rating

Condition (See Table 1).

c. Separate part load data point(s).

5.1.6.1 IPLV and APLV values shall be deter

mined by test at the conditions prescribed in Ta

ble 1.

5.1.6.2 For water-chilling packages covered by

this Standard, Part Load Values (IPLV or

APLV) shall be calculated as follows:

a. Determine the kW/ton at. 100 percent; 75

percent; 50 percent and 25 percent load

points at the conditions specified in Table 1.

b. Use the following equation to calculate

IPLV or APLV:

IPLV or APLV = 0.05A + 0.3B + 0.4C +

0.25D (1)

where: A = kW/ton at 100%

B = kW/ton at 75%

C = kW/ton at 50%

D = kW/ton at 25%

For a derivation of equation (1) see Appendix B.

c. If the package cannot be operated at the

25% load point, operate it at minimum ca

pacity with the entering fluid temperature

(EWT) corresponding to 25% capacity

conditions. Then calculate kW/ton as the

measureu kW divided by 25% of the 100%

load capacity obtained by test.

5.1.6.3 Part load performance data shall be pre

sented in terms of percentage of rated power

input (kW or bhp) [kWJ versus percentage of

rating capacity (tons) [kWj. Water temperatures

shall be adjusted for field fouling allowance per

A7.3. If presented, and not otherwise stated,

part load performance shall be based on the

IPLV conditions shown in Table 1.

5.1.7 Off Cycle Requirements. Off cycle power, if

presented, shall be time averaged power input

(kW).

5.1.8 Published Rating Data. Published rating data

(in catalogs or computer output) shall include

package designation(s), Standard Ratings for each

such package and any additional application rat

ings elected. The rating at any condition shall In

clude:

Compressor/Cooler (All Condenser Types)

a. Nominal voltage and frequencies for which

ratings are valid.

b. Refrigerant selection for which ratings are

valid.

c. Capacity, tons of refrigeration [kW]

3
ARI STANDARD 550-90

Table 1. Part Load Conditions for Rating

IPLV APLV

Cooler (All Types)

100% load LWT * 44F [6.7°C] * Selected LWT

0% load LWT 44F [6.7°C] Same as 100% load

Flow rate (gpm) ** 2.4 gpm/ton [0.043 ** Selected gpmlton

L/s per kW]

Field fouling allowance (F.F.A.) 0.00025 As specified

Condenser (Water-Cooled)

100% load EWT * 8SF [29.4°C] * Selected EWT

0% load EWT ***60F [15.6°C] ***60F [15.6°C]

Flow rate (gpm) [L’s] ** 3.0 gpmlton [0.054 ** Selected gpmlton

• Us per kW] [L’s per kW]

F.EA. 0.00025 As specified

Condenser (Air-Cooled)

100% load EDB 9SF [35.0°C] Selected EDB

0% load EDB ***55F [12.8°C] ***55F [12.8°C]

F.F.A. 0.000 0.000

Condenser (Evaporatively-Cooled)

100% load EWB 75F [23.9°C] Selected EWB

0% load EWB ***5 [10.0°C] ***50F [10.0°C]

F.FA. 0.000 0.000

Corrected for field fouling allowance by using the calculation method described in A7.3.

The flow rates (gpm) are to be held constant at full load values for all part load conditions.

*Condenser entering fluid or air temperature varies linearly from 100% load values to 0% load values.

JWT is leaving water (liquid) temperature.

EWT is entering water (liquid) temperature.

EDB is entering air dry bulb temperature.

EWB is entering air wet bulb temperature.

F.F.A. is field fouling allowance in hrft F/Btu [m 0C,W]

d. Power input requirements, compressor shaft

horsepower (if prime mover is not supplied)

Kilowatt input for open or hermetic drives,

kW (see 5.1.6).

Leaving chilled water temperature, F [°C]

Cooler liquid pressure drop (inlet to outlet),

psi or feet of water [kPa]

h. Pass or baffle arrangements and rated water

flows, gpm [Us]

i. Maximum and minimum recommended flow

rates for.relatively clean water

Condenser (Water-cooled) V

a. Entering condenser water temperatures, F

[°C]

b. Condenser water pressure drop (inlet to Out

let), psi or feet of water [kPa]

c. Statement of field fouling allowances in heat

exchanger

d. Pass or baffle arrangements and rated water

flows, gpm [L’s]

e. Maximum and minimum recommended flow

rates for relatively clean water. (Any limita

tion on water flow rates to minimize erosion,

corrosion, or fouling should take into consid

eration the quality of the water and any ma

terials it may have in suspension, tube mate

rial, as well as the number of expected

operating hours per year.) V

Condenser (A jr-cooled)

a. Entering air dry-bulb temperature to the con

denser, F [°C}

b. Condenser fan motor power consumption,

kW V

Condenser (Evaporatively-cooled)

a. Entering air wet-bulb temperature to con

denser, F [°C]

e.

f.

4
ARI STANDARD 550-90

Rated Full Load Performance

Rated ca

pacity

Rated

b. Condenser fan motor power consumption, See Figure 1 “Allowable Tolerance Curve for Full

kW and Part Load” for graphical representation only.

c. Condenser spray pump power consumption,

kW

d. Statement of field fouling allowance on heat 5.4.2 Full Load. Published ART ratings shall be

exchanger. such that any production package shall, upon test

have a full load capacity not less than 100 percent

5.2 Water-Side Fouling, of its rated capacity less the allowable tolerance

and a full load power input per ton (kW/ton) [kW/

5.2.1 Fouling at Standard Rating Condition. The kW] of not more than 100 percent of its rated kW/

choice of 0.00025 hr sq ft F/Btu [0.000044 m2 °C/ ton [kW/kW] plus the allowable tolerance. The al

W] for coolers, and condensers for the Standard lowable tolerance shall be determined by the equa

Rating Condition field fouling allowance which is tion specified in 5.4.1.

the basis for published rating conditions (see 5.1.1

and 5.1.2.1) provides equipment selections which Water pressure drop in the cooler and condenser

anticipate the effect of typical fouling in cooler and shall not exceed 115 percent of rated pressure drop

condenser water circuits. Fouling tends to reduce at rated gpm, [Us].

capacity and increase power consumption. An ap

plication should remain within the limits of the Example (Full load): (in U.S. Standard Units only

field fouling allowance if acceptable water quality for clarity)

is maintained by treatment, and the heat exchanger

surfaces are periodically cleaned.

5.2.2 Additional Fouling. Conditions such as = 100 tons

water hardness, organic material, suspended solids

and/or water velocity may necessitate the use of a power = 70 kW

greater field fouling allowance than that provided Cooling DTFL = 1OF

in the Standing Rating of equipment.

70 kW

5.2.3 Adjustments for Additional Fouling. Pub- kW/ton = — = .70 —

100 ton lished ratings may include the effects of additional

field fouling allowance. Such ratings shall be de- Allowable Test Performance—

termined by using the methods described in para

graph 5.1.4b. Tolerance = 10.5 — (.07 x 100%) +

(1500)

5.3 Verification of Capacity and Power Requirements. (10 X 100%)

Where verification of capacity and power requirements

is required, it shall be by test in accordance with the

method set forth in Appendix A to this standard. -

= 10.5 — 7 + 1.5 = 5%

5.4 Tolerances. (100 5)

Mm. allowable capacity x 100 = 100

5.4.1 Allowable Tolerance. The allowable test tol- = 95 tons

erance on capacity (tons) [kW], power input per

ton (kW/ton) [kW/kW] and heat balance, shall be (100 + 5)

Max. allowàblë kW/ton = .70 determined from the following equation: 100

Tolerance in percent tons [kWJ, percent kW/ton = .735 kW/ton

[kW/kWJ or percent heat balance

Max. kW at mm. capacity = .735 x 95 = 69.825

= 10.5 — 0.07 x % FL + (1500/(DTFI.. x %

FL))

(U.S. Standard Units DTFL in F.)

[ = 10.5 — 0.07 x % FL + (833.3/DT x %

FL)] 5.4.3 Part Load. The tolerance on part load power

[SI units DTFL in °C] input per ton (kW/ton) shall be the tolerance for

kWfton determined by the equation specified in

where FL = Full Load 5.4.1.

DTFL = Difference between entering and

leaving chilled water temperature Example (Part load): (in U.S. Standard Units only

at full load, F [°C]. for clarity)

)
MU STANDARD 550-90

z

LU

0

LU

0

LU

C)

z

LU

-J

0

= 10.5 — 3.5 + 3 = 10%

(1500)

10 x 50%)

Max. allowable kW/ton = (100 x .70

= 0.77 kW/ton

5.5.4 !PLV and APLV Tolerance. The allowable

tolerance on IPLV and APLV shall be determined

by the following equation:

Allowable Tolerance (percent)

6.5 + 35IDT DTFL in F

I = 6.5 + l9.4!DTj DTFL in

DTFL as specified in 5.4.1 see Figure 2. “IPLV and

APLV Tolerance Curve”

The single number IPLV or APLV, calculated for

the part load conditions which apply, shall not ex

ceed the rated IPLV or APLV by more than the

allowed tolerance.

Section 6. Refrigerant Designation

6.1 The refrigerant designation shall be specified on the

package nameplate.

6.1.1 The refrigerant designation shall be in accor

dance with the ANSI/ASHRAE 34-1989 Standard

Number Designation ofRefrigerants.

Section 7. Voluntary Conformance

7.1 Conformance. While conformance with this stan

dard is voluntary, conformance shall not be claimed or

implied for products or equipment within its Purpose

(Section 1) and Scope (Section 2) unless such claims

meet all of the requirements of the Standard.

Figure 1. Allowable Tolerance Curves For Full And Part Load -.

0

DTFL (SEE 5.4.1)

PERCENT FULL LOAD

Rated Part Load Performance

50% capacity

50% power

k \V/ton

Full load DTFL

= 50 tons

= 35kw

= .70 kW/ton

= 1OF

Allowable Test Performance

Tolerance = 10.5 — (.07 x 50%) +

6
___________________________________________

ARI STANDARD 550-90

Figure 2. IPLV and APLV Tolerance Curve

20

18

16

14

w

C.) 12

w

LU

C)

z

LU

-J

0

6

4

2

0

16 17 18 19 20

DTFL (SEE 5.41) COOLER DT AT FULL LOAD, F

7

3 4 5 6 7 9 10 11 12 13
ARI STANDARD 550-90

APPENDIX A

STANDARD REQUIREMENTS FOR TESTiNG

CENTRIFUGAL OR ROTARY SCREW WATER-CHILLING PACKAGES

e

Section Al. Purpose

A1.1 Purpose. The purpose of this appendix is to pre

scribe a method of testing centrifugal or rotary screw

water-chilling packages to verify capacity and power

requirements at a specific set of conditions.

It is intended that this testing will occur where instru

mentation and load stability can be provided.

It is not the intent of this standard to provide for testing

in typical field installations where steady state condi

tions are often difficult to achieve and provisions for

measurement are not made.

A2. Scope

A2.1 Scope. This appendix applies to centrifugal or

rotary water-chilling packages used to chill water, as

defined in Section 3 of this standard.

Section A3. Definitions

A3.1 Definitions for this appendix are identical with

those in Section 3 of this standard.

A4.1 Test Method.

A4.1.1 The test will measure net cooling capacity

(tons of refrigeration) and energy requirements, at

a specific set of conditions.

A4.1.2 To confirm that steady-state conditions

have been established at the specific set of condi

tions and within the tolerances set forth in A7.2,

three sets of data shall be taken, at approximately

five-minute intervals. To minimize the effects of

transient conditions, test readings should be taken

as nearly simultaneously as possible.

A4.1.3 The test shall include a measurement of

the net heat removed from the, water as it passes

through the coolers by determination of the follow

ing:

a. Water flow rate

b. Temperature difference between entering

and leaving water

A4.1.4 The heat removed from the chilled water

is equal to the product of the chilled water flow

rate, the water temperature difference, and the

specific heat of water.

A4.1.5 The test shall include the determination of

the compressor power requirement. This power

shall be determined by measurement of electrical

input to motor drive (see 5.1.6). For motors sup

plied by others the determination of compressor

shaft horsepower input shall be as outlined in the

test procedure. For air-cooled or evaporatively

cooled condensers, thetest shall include the deter

mination of the condenser fan and condenser spray

pump power requirements.

A4.1.5.1 Non-Electric Drive. Where turbine or

engine drive is employed, compressor shaft

horsepower input shall be determined from

steam, gas, or oil consumption, at measured sup

ply and exhaust conditions, and prime mover

manufacturer’s certified performance data.

A4.1.6 In addition to the determination .of net

heat removed and energy input required, data shall

be taken to prepare a heat balance to substantiate

the validity of the test.

A4.2 Condition of Heat Transfer Surfaces.

A4.2.1 Tests conducted in accordance with this

standard may require cleaning (in accordance with

manufacturer’s instructions) of the heat transfer

surfaces. The as tested fouling factors shall then be

assumed to be 0.0000 hr sq ft F/Btu [0.0000 m2

°C/W].

Section A5. Instruments

A5.1 Instruments shall be selected from the types listed

in ASHRAE Standard Method of Testing Liquid Chill

ing Packages (American Society of Heating, Refriger

ating and Air-Conditioning Engineers, Inc. Standard

30-78).

A5.1.1 Accuracy of instruments selected shall be

in accordance with that specified in ASHRAE

Standard 30-78.

A5.1.2 Temperature measurements shall be made

in accordance with ASHRAE Standard Measure

ments Guide—Sçction on Temperature Measure

ments (American Society of Heating, Refrigerating

and Air-Conditioning Engineers, Inc. Standard

41.1-86).

A5.L3 Flowmeters shall be constructed and in

stalled in accordance with the applicable portion

Section A4. Test Methods

.
ARI STANDARD 550-90

of the latest edition of the ASME “Fluid MetersTheir Theory and Application.” lurbine flow me

ters may also be used in accordance with ANSI!

ISA-PR31.1 (latest edition) “Recommended Prac

tice Specification, Installation, and Calibration of

Turbine Flowmeters.”

A5.1.4 Scales for analog meters shall be such that

readings will be at least one-half of full scale de

flection. All instruments, including gages and ther

mometers shall be calibrated over the range of test

readings.

A5.1.5 Pressure measurements shall be made in

accordance with ASME Power Test Code FTC

19.2, “Instruments and Apparatus, Part 2, Pres

sure Measurement.”

Section A6. Measurements

A6.1 Data to be recorded during the test:

A6.1.1 Test Data.

Compressor/Cooler (All Condenser Types)

a. Temperature of water entering cooler, F [°C]

b. Temperature of water leaving cooler, F [°C]

c. Chilled water flow rate, gpm or lbs/hr [L/sJ

d. Power input to compressor, kW or

e. Steam consumption of turbine, lbs/hr [kg/hr}

Steam supply pressure, psig [kPa]

Steam supply temperature, F [°C]

Steam exhaust pressure, psig or inches Hg.

vac. [kPa] or

f. Gas consumption of turbine or engine,

therms or cu ft per hr, [L/s] and calorific

value, Btu per cu ft, [J!L], or

g. Fuel consumption of diesel or gasoline en

gine, gallons per hr, [L’s] and calorific value,

Btu per gallon [J/L]

h. Cooler water pressure drop (inlet to outlets),

psi or feet of water [kPa].

i. Electrical power input to controls and auxil

iary equipment, kW

Condenser (Water-cooled)

a. Temperature of entering condenser water, F

[°C]

b. Temperature of leaving condenser water, F

[°C]

c. Condenser water flow rate, gpm or lb/hr [L/

s]

d. Condenser water pressure drop (inlet to out

let), psi or feet of water [kPa].

Condenser (A jr-cooled)

a. Dry-bulb temperature of air entering the con

denser, F [°CI

b. Condenser fan motor power consumption.

kW

c. Barometric Pressure, in. Hg [kPa]

Condenser (Evaporarively-cooled)

a. Wet bulb temperature of air entering the con

denser, F[°C]

b. Condenser fan motor power consumption,

kW

c. Condenser spray pump power consumption,

kW

d. Barometric pressure, in. Hg [kPa]

A6.1.2 If chilled water is used to cool the com

pressor motor or for some incidental function

within the package, the temperature and flow

measurements of chilled water must be made at

points beyond such take-offs and returns, so that

the measured rise reflects net cooling capacity.

A6.1.3 If condenser water is used to cool the com

pressor motor or for some other incidental function

within the package, the temperature and flow

measurements of condenser water must be made

at points ahead of such take-offs and returns, so

that the measured rise reflects gross condenser heat

rejection.

A6.2 Auxiliary data to be recorded for general infor

mation.

A6.2.1 Nameplate data including make, model,

size and refrigerant, sufficient to completely iden

tify the water-chilling package.

A6.2.2 Compressor driver or input rpm for opentype compressors.

A6.2.3 Ambient temperature at test site, F[°C]

A6.2.4 Actual voltage, and current in amperes for

each phase, of all electric motor drive.

A6.2.5 Motor, engine or turbine nameplate data.

A6.2.6 Pressure, temperature and exhaust pres

sure for steam turbine drives.

A6.2.7 Fuel gas specification for gas turbine drive,

including pressure, in. water [kPa].

A6.2.8 Heat balance for A7.4

A6.3 Record Data.

A6.3.1 Date, place and time of test.

9
ARI STANDARD 550-90.

A6.3.2 Names of test supervisor and witnessing

personnel.

Section A7. Test Procedure

A7.1 Preparation for Test.

A7.1.1 The centrifugal or rotary screw water-chill

ing package, which has been completely connected

in accordance with the manufacturer’s instructions

and is ready for normal operation, shall be pro

vided with the necessary instruments.

A7.1.2 The test shall not be started until non-con

densabies have been removed from the system.

A7.1.3 At the manufacturers option condenser and

cooler surfaces may be cleaned as provided in

A4.2.1.

A7.2 Operation and Limits.

A7.2.1 Start the system and establish the testing

conditions in accordance with the following toler

ances and instructions:

a. Cooler (All Condenser Types)

(1) The chilled water flow shall not deviate

more than ±5 percent from that speci

fied.

(2) The individual readings of water temper-

• ature leaving the cooler shall not vary

from the specified values by more than

0.5 F [0.3°C]. Care must be taken to in.

sure that these water temperatures arc

the average bulk stream temperatures.

(3) The leaving chilled water temperature

shall be adjusted by an increment calcu

lated per A7.3 corresponding to the spec

ified field fouling allowance.

(4) Part load test capacity must be taken

within ±2% of the full load tons at the

specified part load capacity.

b. Condenser (Water-Coaled)

(1) The water flow through the condenser

shall not deviate more than ± 5 percent

from that specified.

(2) The individual readings of water temper

atures entering the refrigerant condenser

shall not vary from the specified values

by more than 0.5F [0.3°C]. Care must

have been taken to insure that these

water temperatures are the average bulk

stream temperatures.

(3) The entering condensing water tempera

ture shall be adjusted by an increment

calculated per A7.3 corresponding to the

specified field fouling allowance.

c. Condenser (Air- or Evaporatively-Cooled)

The individual readings of water temperature leaving

the cooler and the saturated refrigerant condensing

temperature corresponding to the compressor dis

charge pressure (regulating the condenser air flow if

necessary) shall not vary from the specified values by

more than 0.5 F [0.3°C]. Care must be taken to insure

that the cooler water temperature is the average bulk

stream temperature and the condensing temperature is

measured as close to the compressor discharge port as

practical. For an evaporative condenser calculate an

appropriate correction to be applied to the correspond

ing specified field fouling allowance.

d. Miscellaneous

(1) For electrically driven machines, voltage

and frequency at the unit terminals shall

be maintained at nameplate values within

tolerances of ± 10% on voltage and

±1% on frequency.

(2) For steam-turbine driven machines,

steam conditions to the turbine, and con

denser pressure or vacuum, shall be

maintained at nameplate values.

(3) For gas-turbine or gas-engine operated

machines, gas pressure to turbine or en

gine, and exhaust back-pressure at the

turbine or engine shall be maintained at

name-plate values.

(4) In all cases, the governor, if provided,

shall be adjusted to maintain rated com

pressor speed.

A7.3 Method for Simulating Field Fouling Allowance

at Full and Part Load Conditions.

A7.3.1 Obtain the log mean temperature differ

ence (LMTD) for the cooler and/or condenser us

ing the following equation at the specified field

fouling allowance (ff 5).

LMTD = in (1 ± S)

A7.3.2 Derivation of LMTD:

= (ts — ce) — (t5 —

ç,,) LMTD

in Ic —_t1

c — t_,J

(Al)

S

.)

.
ARI STANDARD 55O-9O”

(t, — t)

— tc,j) + (tc,i —

L t, —t,

The incremental LMTD (ILMTD) is determined using

the following equations:

ILMTD = if,,,() (A2)

where: ff = specified field fouling allowance

q = Total heat rejection rate for condensers

or net refrigeration capacity for coolers

Btuh [W].

A = Total heat transfer surface, sq ft [m21

where: A = A. for fouling inside tubes

A = A, for fouling outside tubes

A7.3.3 The water temperature difference TD

needed to simulate the additional fouling, TD, can

now be calculated:

TD = S,,, — S (A3a)

TD, = s, —

- R (A3b)

“ e—l

= LMTD — ILMTD

Where: S = small temperature difference as

specified

S = small temperature difference as

tested in cleaned condition

The water temperature difference, TD, is then

added to the condenser entering water tempera

ture or subtracted from the cooler leaving water

temperature to simulate the additional fouling fac

tor.

A7.3 .4 Example—Condenser Fouling Inside

Tubes (in U.S. Standard units.only, for clarity)

Specified field fouling allowance ff5 = 0.00025

hr sq ft FIBtu

Condenser load, q = 2,880,000 Btuh

Specified condenser leaving water temp. T1 =

95F

Specified condenser entering water temp. =

85F

lnside* tube surface area, A1 = 550 sq ft

*(Since fouling is inside tubes in this example)

Saturated condensing temperature. ç = IOIF

= t, — t, = 101 —95 = 6°F

R ç, — t_e = 95—85 = 10°F

LMTD = R (Al)

In (1+ RIS)

10 — 10.2 — In (1 + 10/6) =

if,,, = 0.00025

ILMTD () (A2)

12,880,000\ = 0.00025 1 550 ) = 1.31°F

TD,, = ,,

— R (A3b)

1 e—1

Where: — R

-LMTD - ILMTD

= 6.0 — 4.8

= 1.2°F

The entering condenser water temperature for

testing is then raised 1.2F to simulate the field foul

ing allowance of 0.00025 hr sq ft °F/Btu. The en

tering condenser water temperature will be 85 +

1.2 or 86.2F.

A7.3.5 Symbols and Subscripts. The symbols and

subscripts used in Equations Al through A3b are

as follows:

Symbols:

Where: R

A = Total heat transfer surface, sq ft [m21

A0/A, = Ratio of outside to inside surface area

e = Base of natural logarithm

q = Total heat rejection rate,. Btuh [W]

r = Heat transfer resistance (hrft 2F/Btu)

[m2°C/W]

R = Water temperature range = absolute

value (t,,, 1 — twe,) F[°C]

S = Small temperature difference = abso

lute value (t3 — F [°C]

t = Temperature, F [°C]

U = Overall heat transfer coefficient

(Btu per hr, sq ft. F) [W1m 2 °C]

ff, = specified field fouling allowance

11
ARI STANDARD 550-90

Subscripts:

a = additional fouling

e = entering

c = cleaned

f = fouled or fouling

= inside

o = outside

= leaving

s = saturated vapor

w = water

sp = specified

A7.4 Heat Balance-Substantiating Test.

A7.4.1 Calculation ofHeat Balance. In most cases,

heat losses or heat gain caused by radiation, con

vection, bearing friction, oil coolers, etc., are rel

atively small and may or may not be considered in

the overall heat balance.

Omitting the effect of the small heat losses and

gains mentioned above the general heat balance

equation is as follows:

where

qe.., ± winpul = q

q,, = net cooling capacity of liquid.

cooler, tons [kWj

= compressor work input as defined

in Paragraphs (a), (b), or (c) below

q = net heat rejected to the condenser,

tons [kWJ

a. In a hermetic package, where the motor is

cooled by refrigerant, chilled water or con

denser water, the motor cooling load will be

included in the measured condenser load,

hence

W,,,, = electrical power input to the

compressor motor expressed in

tons [kWl

b. In a package using an open-type compressor

with motor and external gear drive:

‘‘input = — qgear

and

W,,, = power input to the compressor

shaft, expressed in tons [kW]

qmo,or = power delivered by prime mover

expressed in tons [kW]

qgear = friction loss in gear box, tons

[kWJ

The value of qprjme mover shall be determined

from the power input to prime mover using

certified data from the prime mover manu

facturer.

The value of qge.r shall be determined from

certified gear losses provided by the gear

manufacturer.

c. In a package using an open-type compressor

with direct drive and the prime mover not

furnished by the manufacturer:

For determination ofW10,for turbine or en

gine operated machines, the turbine or en

gine manufacturer’s certified power input!

output data shall be used.

W,,, 3, = power input to the compressor

shaft, expressed in tons [kWJ

In the case of motor drive:

= power measured at motor ter

minals.

A7.4.2 Percent Heat Balance. Heat balance, in

percent, is defined as:

q,, + — q,., x 100 (A4)

For any test of a liquid cooled chiller to be accept

able, the heat balance (percent) shall be within the

allowable tolerance calculated per 5.4.1 for the ap

plicable conditions.

For air or evaporatively cooled condenser, it is

impractical to measure heat rejection in a test,

therefore a heat balance cannot be calculated.

Section A8. Calculation of Results

A8.1 Capacity and Power.

A8.1.1 The capacity in tons [kW] shall be obtained

by the following equations:

c w(t — t1) tons =

12,000

where

[kW = 4.187 c/W (te — t1)]

(AS)

c = specific heat of water at average water

temperature, Btu/(lb.F) [kJ/kg.°C]

w = weight flow rate of chilled water, lb per

hr [kg/s]

0)

0

12
ARJ STANDARD 550-90

= temperature of water entering the

cooler, F [°C]

= temperature of water leaving the

cooler, F [°C]

A8.1.2 Power consumption shall be determined as

follows (consistent with 5.1.6):

a. For motor driven centrifugal or rotary screw

compressors where the motor is supplied by

the manufacturer, the compressor power in

put shall be measured as close as practical to

the compressor motor terminals. If a fre

quency conversion device or motor starter is

furnished as part of the compressor circuit,

the compressor power input shall be meas

ured at the input terminals of the frequency

converter or motor starter. For remote start

ers or frequency converters, line losses shall

be subtracted. If the water-chilling package

being tested is not equipped with the starter

or frequency converter furnished for it, then

a starter or frequency converter of similar

type shall be used for the test.

b. Power consumption of auxiliaries shall be the

time-averaged power consumplion of thesc

devices during normal operation of the pack

age.

c. For open-type compressors, where the motor

and/or gear set is not supplied by the manu

facturer, or for engine or turbine drives, the

compressor shaft input shall be determined

as stated in A7.4.1 b or c.

d. For air-cooled or evaporatively-cooled con

densers, the additional condenser fan and

condenser spray pump power consumption

shall be measured as close as practical to the

motors.

A8.1.3 Validity of Test. Calculate the heat balance

for each of the three test points (A4.l.2). All three

heat balances must be within the tolerance speci

fled (A7.4.2). Then average the data taken

(A6.l.1) from the three test points and calculate

capacity and power input per A8.1.1 and A8.I.2

using averaged data for reporting purpose.

APPENDIX B

DERIVATION OF INTEGRATED

PART LOAD VALUES (IPLV AND APLV)

Section Bi. Purpose

B1.1 Purpose. This appendix shows an example of the

calculations for determining Integrated Part Load Val

ues (IPLV) or Application Part Load Value (APLV).

Section B2. Scope

B2.1 Scope. This appendix is for equipment covered by

this standard.

Section B3. Equation and Definition of Terms

B3.1 General Equation (see 5.1.7.2)

IPLVorAPLV = 0.1(A) 05(B+c)

F (C+D\ +0.3 2 1 + 0.1D (1)

where: A = kW/ton [kW/kW] at 100% load point

B = kW/ton [k-W/kW] at 75% load point

C = kW/ton [kW/kW] at 50% load point

D = kW/ton [kW/kW] at 25% load point

And referring to Section B4-Calculation Example: (in

U.S. Standard units only for clarity)

or simply

IPLV or APLV = O.05A + 0.3B + 0.4C + 0.25D

IPLV or APLV = 0.05 (0.7)

+ 0.30 (0.62)

+ 0.40 (0.60)

+ 0.25 (0.71)

IPLVorAPLV = 0.035 + 0.186 + 0.240 ± 0.178

= 0.639

13
ARI STANDARD 550-90.

Section 84

EXAMPLE CALCULATIONS

% Full Mfrs. Net PLF Mfrs. Part Avg. Part PLF Diff. Avg. kW/ton x PLF Diff. = Weighted

Load Cap.’ Cap. (Tons) 2 Factor 3 Load kW/ton 2 Load kw)ton Avg.

100% 500 1.0 0.70

= 0.66 (1.0—0.9)=0.1 0.66 x 0.1 = 0.066

75% 375 0.9 0.62

= 0.61 (0.9—0.4)=0.5 0.61 x 0.5 = 0.305

50% 250 0.4 0.60 -

= 0.66 (0.4—0.1)=0.3 0.66 x 0.3 = 0.198

25% 125 0.1 0.71

= 0.71 (0.1—0.0)=0.1 0.71 x 0.1 = 0.071

0% —--- 0.0 —

Single number IPLV or 0.64

APLV

NOTES

‘For centrifugal and rotary screw type water chilling packages as covered by the standard, the kW/ton and capacities used to calculate the single

number IPLV are to be at 100%, 75%, 50% and 25% of full load capacity.

2A11 part load capacities and kW/ton are at part load rating conditions as determined by the standard.

3Part load factor from Figure B-i.

0

G
ARI STANDARD 550-90

FIGURE Bi EXAMPLE PART LOAD FACTOR CURVE

5 .____

1’

PART LOAD FACTOR CURVE

Lu

>

D

0

I

LI

-J

0

0

0 20 40 60 80 100

PERCENT OF FULL LOAD CAPACITY OR DISPLACEMENT AT

PART-LOAD CONDITIONS