# 1987 STANDARD 

# for

.IJP;

... I'.. AIR-CONDITIONING 

## & REFRIGERATION INSTITUTE 

# DESUPERHEATERI WATER HEATERS

I Standard 470 

# I
EXHIBIT 1

1501 WILSON BOULEVARD ARLINGTON, VIRGINIA**22~09** 

# 1987 STANDARD 

# for



# ,

liP. 

# .... ,. A I R,COND ITI O NI NG & 

## REFRIGERATION INSTITUTE 

# DESUPERHEATERI WATER HEATERS



# I Standard 470 

# I

EXHIBIT 1

1501 WI LSO N BOULEV A RD • A R LINGTON, VIR G IN IA 22", 09TABLE OF CONTENTS
PART PAGE Section I. Purpose I Section 2. Scope 1 'Section 3. Definitions 1 Section 4. Standard Equipment and Accessories I Section 5. Testing and Rating Requirements I 

### Section 6. Safety Recommendations and Sanitary Provisions 4 Section 7. Marking 4 Section 8. Voluntary Conformance 4
APPENDIX A. METHOD OF TESTING DESUPERHEATER/WATER HEATERS Section A 1. Purpose 5 Section A2. Scope '5 Section A3. Definitions 5 Section A4. Expression of Test Results 5 Section AS. Test Methods 5 Section A6. Instruments, Test Apparatus, and Thermodynamic Properties 6 Section A 7. Test Procedure 6 Section A8. Computation of Results 7
TABLES Table I. Standard Rating Conditions 4



### NOTE This standard supersedes ARI Standard 470-80.

PrICe $8.00 Printed in U.S.A. © COPYRIGHT; 1987 by Air-Conditioning and Refrigeration Institute 

### PART Section I. Purpo se Sec ti o n 2. Scope

' Section 3. De fini tio n s TABLE OF CONTENTS


### PAGE

.. I

. . . . . . . . I ...•. 1 

### S ec t io n 4. St and a rd Eq uipm e nt a nd Accesso ri es Sec ti on 5. T est in g and Rating R eq uireme nt s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I


### Sec ti o n 6

. Safet y R eco mm endati o n s a nd San itary Provi s ion s .. . .. . Sec ti o n 7

. Mark ing

. . Sec ti on 8. Vol u ntar y Co n for m a nce .. APPENDIX A

. METHOD OF TESTING DESUPERHEATER/ WATER HEATERS 

### Sec ti o n A I

. Sec ti on A2. Pur pose . .. . Scope

. ... .......... ... .. . Sec ti on A3. Defi niti o n s ....... . Section A4. Sec tion A5

. E xpr ess io n o f Te st Res ult s ... .. ..... ................ ... .... .. . ..... . Te st Me th ods

.. Sec tion A 6. In s truments. T es t Apparatus. and The rm odynamic Pro perties Section A 7. T est Pr oced ure Sec tion A8

. Co mput at i on of Re s ult s TABLES 

### Table J

. 

### Standard Ra li ng Con diti ons



### NOTE This standard supersedes AR I 

### Standard 470.s0. .... I



### . . . 4

. . .. . 4

. . .. 4

. .... 5 ..5

. .... 5 ..5 

### ;

. .. 6

. .. 6

.. . 7

. 4

I'" e ll S B

. OO P"moo III U

. S

. A CI COPYRIGHT, 1987 by Air-Cond Itioning and Relrigeratiollinsfitu/e

### _______________________ ARI STANDARD 470·87 

# DESUPERHEATER/WATER HEATERS
Section 1. Purpose 1.1 

### Purpose. The purpose of this standard is to establish, for desuperheater/water heaters: definitions; a specification of what constitutes standard equipment; procedures for testing and rating; safety provisions; and requirements for marking. 1.1.1 

### This standard is suggested as a guide for the industry, including manufacturers, distributors, contractors, consulting engineers, and users of desuperheater/water heaters. 1.2 

### Review and Amendment. This standard is subject to review and amendment as the art of the industry advances. Section 2. Scope 2.1 

### Scope. This standard applies to desuperheater/ water heaters supplied as separate components, as defined in 3.1. 2.2 

### Exclusion. This standard does not apply to desuperheater/water heaters supplied as components of factory-assembled refrigeration or airconditioning units. Section 3. Definitions 3.1 

### Desuperheater/Water Heater. A factory-made assembly of elements by which the flows of refrigerant vapor and water are maintained in such heat transfer relationship that the refrigerant vapor is desuperheated and the water is heated. 3.2 

### Useful Heat Exchange Effect. The useful heat exchanged between the refrigerant vapor and the water being heated. This value is the product of the mass rate of water flow, the specific heat of water and the water temperature rise, expressed in Btuh (W]. 3.3 

### Total Heat Exchange Effect. The total heat removed from the refrigerant in the heat exchanger. This is the sum of the useful heat exchange effect and the heat loss through the external surfaces of the heat exchanger to the ambient air. 3.4 

### Nominal Refrigerating System Capacity. The cooling effect produced by the product of the mass flow of refrigerant and the difference in enthalpy between the refrigerant entering the evaporator and the refrigerant leaving the evaporator. 3.5 

### Cleaned Tube Capacity (Btu/h). Cleaned tube capacity in Btu per hour [W] is the total heat exchange effect (3.3) in the operation of the heat exchanger with cleaned tubes at the rating condition chosen per Table 1. 3.6 

### Field Fouling Allowance. Provisions for anticipated fouling factor during use. 3.6.1 

### Fouling Factor. The thermal resistance due to fouling on the heat transfer surface. 3.7 

### "Shall", "Should", "Recommended", or "It Is Recommended". "Shall", "should", "recommended", or "it is recommended" shall be interpreted as follows: 3.7.1 

### Shall. Where "shall" or '\shall not" is used for a provision specified, that provision is mandatory if compliance with the standard is claimed. 3.7.2 

### Should, Recommended or It Is Recommended. "Should", "recommended" or "it is recommended" is used to indicate provisions which are not mandatory but which are desirable as good practice. Section 4. Standard Equipment and Accessories 4.1 

### Standard Equipment. The following items shall be required as standard equipment: 1. Refrigerant inlet connection 2. Refrigerant outlet connection 3. Water inlet connection 4. Water outlet connection 5. Data plate or other suitable marking Section 5. Testing and Rating Requirements 5.1 

### Published Ratings. Published ratings consist of Standard Ratings and application ratings. Such ratings shall be based on tests of desuperheater/hot water heaters with the refrigerant specified in the ratings. The tests shall be conducted in accordance with the procedure contained in Appendix A. 5.1.1 

### Published ratings shall state all the pertinent operating conditions and shall include the following: a. Refrigerant designation b. Entering refrigerant temperature, F (0C] 

### c. Entering refrigerant pressure psi (kPa] d. Useful heat exchanger effect, Btu/h [W] e. Water flow rate, gpm [Lis] f. 

### Water pressure drop, psi or feet of water (kPa] g. Refrigerant side pressure drop, psi (kPa] h. Refrigerant mass flow rate, Ib/hr [kg/s] i. Fouling factor (water side) fe·hr·F/Btu 

### [m 2 

### .oCIW] plus at least one of the following:

j. Temperature entering water, F rOC] k. Temperature of leaving water, F rOC] ________________________ ARI STANDARD 470·87 

# DESUPERHEATER/WATER HEATERS
Secti on 1

. Purpose 1

. 1 

### Purpose

. The p u rpose of t hi s sta nda rd is to establish, f or desu p e rh ea t er/water hea lers: defini tions; a specifica tio n of wh at cons titu tes sta nd a rd eq uip ment; procedu res f or testi n g a n d rati ng; safe ty prov isions; and req uire me nts for mar kin g. 

### 1.1.1 This standard is s uggested as a g uide fo r the ind u stry, incl u d ing ma nu facturers , d is tri b u tors , 

### contrac tors , cons ul ting eng ineers , a n d u se rs of des u pe rh eater / water hea le rs. 1.2 Review and Amendmefll

. T his sta n dard is s u bject to rev iew a n d amendment as t he art of the ind u stry adva n ces. 

### Section 2. Scope 2

. 1 Scope. T his s ta n dard applies to des uperheate r l wate r hea lers s upp li ed as separate components, as def ined in 3.1. 2

. 2 

### Exclu.sion. T h is standard d oes not app ly t o desuperheate r / watcr hea te r s suppl i ed as compone n ts of facto ry-assemb led refrigeratio n or a ircondit io ning un its.
Section 3

. Defini ti ons 

### 3

. 1 Desuperheaterl W arer Heater

. A factory-made a sse mb ly of e lements by which the flows of ref ri ge r ant vapor and water are maintai ned in s uch hea t tr ansfer relations hip t h a t th e refrigerant vapor is des upe rh eated and the water is hea ted. 

### 3. 2 

### Useful Heat Exchange Effect. T he useful heat exc h anged between the r efrigera nt va p or a nd t he wa te r be in g heated. T hi s va lu e is the product of t he mass r a te of wa ter fl ow, th e speci fi c hea t of wa ter and th e water tempera t ure rise , exp ressed in Btu h [W]. 

### 3

. 3 Total H eal Exchange Effect. T he total heat removed from th e refri gera nt in th e heat exchanger. Th is is t he sum o f th e u sef ul heat exc h ange effcct and t he hea t loss thro u g h t he externa l su rfaces of t hc heat exc h anger 10 

### t he amb ient a ir. 3

. 4 

### Nominal Refrigerating System Capacity. The cooling effec t produced by t he produc t of the mass flow of refrigera n t and the d ifference in enthalpy between th e refr ige ra nt e nte ring t he evaporator and th e re fr igerant leaving th e eva p orator. 

### 3.5 Cleaned Tube Capacity (Btulh). Clea ned t ube capacity in Bt u per hou r [ W I is the total hea t exchange effect (3.3) in the operation of t he heat excha nger with cleaned t ubes at the rati ng con d it io n chosen per Tab le I. 

### 3.6 Field Fouli ng Allowance

. Provis io n s for an ti cipated fo u ling facto r d uring u se. 

### 3

. 6 .1 

### Fouling F actor. T he t herm al resis tance d u e to fo uli ng o n the hea t tr ans f er s urf ace . 

### 3. 7 

### " Shall", "Should", " Recommended ", or " I t 

### I s Recommended ". "Shall", "s hou ld ", " recommended ", or " it is reco mme n ded " sh a ll be in te rpre ted as follows: 

### 3

. 7. 1 

### Shall. Whe re "s h all" or 'Is h all not" is used fo r a p rovis io n specified

. t h a t provision is ma ndatory if co mp li ance wi t h th e st a nd a rd is cla imed. 

### 3.7 .2 

### Should, Recommended o r It 

### Is Recommended

. "Shoul d ", " r eco mme nd ed " or "it is reco mm ended" is u sed to in d icate p rov is ions whic h a re no t m anda tory but whi c h are desirable as good pract ice. Section 4. Standard Equipment and Accessories 4.1 

### Standard Equipment. The fo ll ow in g ite ms sha ll be 

### req u ired as standard e qu ip me nt : 1. Refri gerant inle t connec ti o n 2. 

### Refri ge rant ou tl et con nect ion 3. 

### Wa ter inlet connectio n 4. 

### Wate r out le t connec t io n 5. 

### Da ta p l ate o r other suitab le ma r kin g Section 5. Testing and Rating Requ i rements 5. 1 

### Published Ratings. Publishe d ratings consist of S tanda rd Ra t in gs a n d ap pli cat ion ratings

. S uch rati ngs s hall be based on tests of des upe rh ea t er/ hot wat e r heaters 

### wi th th e refr ige r a nt spec if ied in th e rat ings . The tests sha ll be conduc ted in accorda nce with th e p rocedu r e contained in Ap p endix A. 5. 1.1 

### P u blis hed r atin gs s h a ll sta te all the perti

ne n t o p erat ing co n d iti o n s a n d s h all include the f o ll ow ing:

a. Refrigerant des ignat ion b. E nte ring re fri gerant tempera ture, F [0C] 

### c. En tering refrige ran t press ure psi [kPaJ d. 

### Use f u l heat excha nger e ff ec t , B t ufh [Wl e. Wat er How r a te , gp m {Us ) f. 

### Water pressu re drop , psi or fee t of water ( kPa] 

### g. Refrige ran t s ide p ressu re d r op , ps i [kP aJ h

. Refr igerant mass fl ow rate, lb/hr [kg/s] i. 

### Fouli ng fac to r (water si de) fe·hr·FlBtu 

### (m' ,"OWI p lus a t least o ne of the fo ll ow i ng:



### J

. Tempera t ure ente ri ng wat e r , F {OCJ k

. Temperature o f leaving water , F [0 C]

### ARI STANDARD 470-87

_ 

### 5.1.2 Published ratings may also include a nominal refrigerating system capacity. The nominal system capacity in tons shall be based upon a total heat transfer effect in the desuperheater/water heater of 2000 Btu/h 

### [588 W] per ton of total system capacity at the 75 F [23.9 0c] 

### entering water temperature, air-cooled conditions shown in Table 1. 

### 5.1.3 Published ratings shall be accompanied by the following information: a. Design pressures for water-side and refrigerant-side, psig [kPa] b. All connection sizes and types c. Shipping weight d. Operating weight (including refrigerant and water) e. Overall dimensions f. 

### Construction type and details g. Minimum water flow rate at minimum entering water temperature h. If 

### only clean tube ratings are published a statement shall be included to contact the manufacturer if fouled tube ratings are required. 

### 5.2 Standard Ratings. Published ratings shall include the Standard Rating, given for at least one of the Standard Rating Groups shown in Table 1 and properly identified as the Standard Rating. Standard Ratings shall be based on tests with initially clean tubes. Water-side and refrigerant-side fouling shall be assumed to be 0.000. 

### 5.3 Application Ratings. Application ratings give performance data under operating conditions other than those shown in Table 1. 

### Whenever application ratings are published or printed, they shall include, or be accompanied by the Standard Rating clearly designated as such, including a statement of the conditions at which the ratings apply. Application ratings shall contain all information shown in 5.1.1. When application ratings include water-side field fouling allowance(s) they shall be calculated by the method specified in 5.4. Published ratings shall be subject to the tolerances of this standard. 

### 5.3.1 Either application ratings or a method of adjusting the cleaned tube ratings may be presented to show the effect of various water-side field fouling allowances. These calculation methods or method of adjusting these ratings shall be calculated in accordance with 5.4. 

### 5.3.2 The manufacturer should provide published information as to the maximum recommended flow rate to minimize erosion and prevent refrigerant from condensing in the desuperheater. 5.4 

### *Determination of Ratings. Ratings shall be determined in accordance with the following:
'Note: Where steady state operation is in a condensing mode, this analysis will be in error. 

### 2 5.4.1 Cleaned Tube Ratings. Published ratings shall be determined with initially cleaned tubes at conditions specified for the selected rating group in Table 1 and conducted in accordance with 5.1. The results of these tests shall be accepted as including a fouling factor of 0.000 

### sq ft

. hr

. F/Btu [0.000 

### m2 • 

### °C/W] 

### 5.4.2 Fouled Ratings. From the results of the cleaned tube tests, calculate the cleaned tube overall heat transfer coefficient, U c ' 

### Then, mathematically add the specified fouling resistance to the reciprocal of the cleaned tube U c 

### and <:alculate the fouled ratings for publication, using the following methods, as applicable.

(a) Tube-in-tube (counter flow arrangement shown -parallel flow also covered).**~( ~e**  

# + • n n**tw,,~** 

### j:,

.... t,cf 

### (b) Single tube pass shell-in-tube (counter flow arrangement shown-parallel flow also covered).

# "'-I~_----.-..-I-"· o 

# ,**~f** 

### (c) Coil-in-shell, single pass (counter flow arrangement shown

- parallel flow also covered). t,f]{ 

# t

I I I \,..----, 1'
.... _-_ ... 

# : --- .... i<:**-~** 

### J,,,,.,

__ ') i' '" I

__ ........ '.... I ,.. 

### , 

### , '--'" 

### \

.......... 

## --, 1" / I \.**~f~,-,----,'~_---J**



# t t.ve ARI STANDARD 470-87

_______________________ _
S

. l .Z Publish ed r a tin gs may 

### also include a no mi

na l re frig e rating syste m capac ity. Th e nominal system capacity in t ons s hall be ba sed upon a lo lal h ea l tran s f e r e ff ec t in th e d es uperheat e r/watcr 

### hea te r of 2000 Btulh (588 Wl per ton of total 

### sys tem ca paci t y a t th e 75 F [23.9 °C ) en t e ring water temperatu re, air -coole d co n ditions shown in Tab le I. 5.1.3 Pub li s h ed ralings s hall be accompanied by th e fo ll owing inf o rmati o n : a. De s i g n pressures for water-side and re fri ge rant -s ide. p sig rkPa) b. All co nne c ti o n s izes and l ype S c. Shipping we ig ht d

. Operating weight (including refrig e rant and water) e . Ove ra ll dim e n s ion s f. Co n s tru c t ion 

### type and de t ai l s g. Minimum wa ler fl o w r a le al minimum e nt e r ing wat e r tempe ralUr e h

. If on ly cl ea n tube r a tin gs are publi s hed a s tatem !:·nt s hall be included to cont act the manufacture r if fouled lube ratings are required

. 

### 5

_

2 Standard Ratings

. Publi s he d ratings s h a ll include th e S tandard Rating , given for at lea s t o ne of th e Sta n dard Ratin g G ro u ps s hown i n Table 1 and properly identifi e d as t h e Standa rd Rating

. S t andard Ral i ngs s h all be based on tes ts with initi a ll y cl e an tubes. Water- s ide and refrigera nt -s ide foulin g s h a ll be ass um ed to be 0 .000. 

### 5.3 Application Ratings. Application rati ngs give pe rforman ce data und er operati n g co ndition s other th a n t h ose s ho wn in Tab l e I. Whenever application ratin gs are publi s hed or printed , th ey s hall include, or be ac co mpani ed by the Standard Ratin g clearl y designated a s s uc h , includin g a state me nt of the conditions at which th e r ati n gs app ly. App lication rating s s hall co ntain a ll inf o rmati on s hown in 5. 1.1. When a pplication ra tin gs include water-side fi e ld fou li ng a llowance( s) they s hall be calcu la ted by the me thod spe cified in 5.4

. Publi s hed rat in gs s h a ll be s u bject to the to leran ces of this standard

. 

### 5.3

. 1 E ith e r application ratin gs or a method of adju s tin g the cleaned tube rating s may be pre se nted to show th e effect of various water-side field fou lin g a ll owa n ces . The se calcu lat io n meth ods o r me thod o f adjusting these rating s s hall be calc ulated in acco rd a nce with 5.4. 

### 5

. 3.2 The m a nufactu r er s h ould provide pub

li s h e d i nf o rm a ti on as t o the maximum r ecomme n ded flow rate to minimize eros i o n and preve nt refrige ran t from co ndens in g in th e de s uperh eater. 

### 5.4 ., De termination of Ratin gs. Rating s s hall be d e ter

mined in accorda nce with th e following :

' Note : Whe re steady scate o peration is in a condensi ng mode, this a nal ys is will be i n e rror . 

### 2 5.4

. 1 Clean ed Tube Ratings . Publi s hed ratin gs s hall be dete rmined with i nitiall y cleaned tu bes at**nditi s**  spec ified for the s elected rating g roup In Table 1 a nd co ndu c ted in accorda nce wit h 5. 1. Th e resu lt s of these tests shall be accepte d as in

cludin g a f o ulin g fa ctor of O .OCIO 

### sq ft

. h r . FlBtu 

### [0.000 

### m'

. °CIW j 

### 5

. 4

. 2 F o uled Ra tings. From the results of th e cleaned tube tes t s, calc ulate th e clea n ed tube overa ll heat tran s fer coe fficient , U c • Then , mathemat

i ca ll y add th e specified fouling resi s tan ce to th e re ciproca l of th e clean e d tube**~** and calculate th e fou l ed ratin gs for publication , using th e followin g methods , a s ap pli ca bl e.

(a) Tube

- in

- t ube (co unter fl ow a rrangement s h ow n - p ara ll el fl o w a lso covered).

(b ) S in gle tu be passs he ll-in

- tube (co unt e r n ow a rr ang e m e n t show n - parall e l fl ow al so cove red)

.

# ~1'-------------rrF**o I-** **~·** + l" (c) Coi l

- in -s hell , s ing le p ass ( co unler fl ow arrangemen t s ho wn - parallel flow al so cove red).**~**

### ________________________ ARI STANDARD 470-87

Obtain U c from the following equation U - q

c - A 

### x (LMTD)c where (LMTD)c is defined by: Counterflow Parallel Flow Now calculate the following:
Chot 

## = (W 

### cp)r 

## = hot fluid (refrigerant) capacity rate at rating conditions, Btu/(hr F) [WfOC) Ccold 

### = (W 

### cp)u' 

### = cold fluid (water) capacity rate at rating conditions, Btu/(hr F) [W/°C)

Flow Length Flow Length the smaller of Chot or Ccold the larger of Chot or Ccold 

### Cmin (tre

- lwe), Btu/hr. [W] (R

t )

# ~Cmin) , dimensionless where 

### R t is based on area A for counterflow:

for parallel flow: The actual heat transfer under fouled conditions,**~,** is calculated from

= E 

### qmax where E is determined for either counter flow or parallel flow arrangements of the exchanger types shown in 

### 5.4.2, items a, band c. Counterflow:

Symbols Total heat transfer area, ft. 2 [m 2 ] Flow-stream capacity rate (Wep), Btu/(hr F) [WfOC) Specific heat at constant pressure, Btu/(lb m F) [kj/kg .0C] Base of natural logarithm Log mean temperature difference, F rOC] Number of exchanger heat transfer units Total heat transferred, Btu/h. 

### [W] Total thermal resistance, hr sq ft F/Btu [m 2 ·°c/W] 1 - 

### (Cmin/Cmax) e-Ntu(l
- 

### c",in IC l7w:r) Parallel flow E =

E = 1 - eNtu(l + 

### c",in1c",ax) 1 

### + Cmin/Cmax Now having the actual heat transfer under fouled conditions, the leaving water and refrigerant temperatures can be calculated from: 

### tree t,.'e 

### +**~/Ccold** 

### tre tre
- qJC hor The combination of**~,** 

### tree and 

### tre define the fouled ratings at the given operating conditions.

A C c"

e LMTD N

tll q R A 

### x (LMTD)c q 

## Rc =_1 

### U

c

2. Basing calculations on inside surface area The next step in determination of fouled ratings is the calculation of the total thermal resistance including fouling. This is found by adding the specified fouling resistance to the cleaned-tube overall resistance, as illustrated below. The total thermal resistance is equal to the reciprocal of the overall coefficient of heat transfer.

A. Refrigerant Outside Tubes (fouling inside) 1. Basing calculations on outside surface area

2. Basing calculations on inside surface area**~;** = 

### R,.; 

### + rn B. Refrigerant Inside Tubes (fouling outside) 1. Basing calculations on outside surface area



### 3 ________________________ ARI STANDARD 470-87

Obta in U

... from th e f o ll o wing eq uation 

## u - q

... - A 

### x (L MTD)

.. where ( LMTD ).. is defin ed by : 

### Cow li erflow P a rallel Fl ow

## ~t**"**

# ~~t**.' ~**  

### t
. , Flow L e n gth
f o r co unt e rfl ow:

for parallcl fl ow : R ow Length

( LM T D ) , =**(~ ,**  - 

## <.',)

-**(~ ,**  

## - <. . )**'** 

# \ell

n Irt' t

..**J** T h e to l al th erma l resistance is e qua l to th e rec ip

ro ca l of the ove r a ll coeffic ie nt o f he al tr a n s f e r. 

### R" =

_ I = A x ( LMTD) , 

## u , q The n e xt s te p in determination o f foul e d ra tin gs i s 

### th e c alcul a ti o n of th e to tal th erm a l res istan ce includin g f o ulin g. Thi s is found b y adding th e specified foulin g r es is tanc e to th e cl ea ne d- lube overall res is tan ce , as illu s trated be l ow. A

. Re frigerant Out si d e Tub es (f o ulin g in s id e) I. Ba s in g c alculati o n s o n o ut s id e s urfa ce area

2

. B asing calculations o n i nsi d e surface a rea**I** = R,.. I 

### + T If B

. Refri ge rant Ins ide Tubes (fo ulin g o ut side) J. Ba si n g ca lculati o n s o n ou ts id e s urf ace a re a 

### R

Ia = 

### R.- u 

### + r/<> 2. B asi ng ca lculati o n s on ill s ide s urfa ce a r e a Now ca lculate th e f o ll ow in g: Cit'" = (W 

### c,,)r = h o t flu id (re fri ge rant ) ca pa c ity r a te at rating c onditions , BtU/(hr F) [ W rC]**old** = (W c p )

... = cold fluid (wa te r ) capac it y rat e a t r ati n g co nditi ons , Blu / ( hr F) [W / "C] 

### c",in = the s m a ller of 

# c...", or 

### c"Old c",,,

... = th e l arge r of 

## 4", o r**d** 

### q", ,,...**c". ~**  

### (1,.,

- '- ) , Bt ulhr. [ W]
NIII = (Rr)

## c""n**)** , dimension less

w here Rr is ba sed o n area A The a c tual h ea t transfe r under fouled co ndi

ti ons, q" i s ca lculat e d from

C!J = f q
... "

... wh e re E is d e te nnined for eithe r counter flow o r parall e l flow a rrang e ments of th e exchanger ty pe s shown in 

### 5. 4.2 , ite ms a , band c. Cou nt erfl ow:

, =**c--c~ ~-~e~** **~N~' ~(t~** **C.~,~" C.~.~r** **~)~_c** 1

- (C "'in / c"."

... ) e Nfu(l
- c",f M ICm"r) Para ll e l fl ow
f = 1

- c=N,u(1 + c",iM 1c",ar) 1 

### +**C", C",** 

### .. ... Now havin g the act ual heat tran s fer un der f ou led cond it i o n s, the lea vi n g water a nd refrig e r a nt temp e ratures ca n be calculated fr o m : t,.. ( 

### l" ., 

### + <trIc.. o ld

Th e co mbin a ti on of q" 

### t..

... a nd 1,.

.. defin e the f o uled ratin gs a t the gi ve n ope rating conditions

. Symbols A T o tal h eat tr a n s f e r area , ft. 2 (m 1 ] C Fl o w-s trea m c apacit y r a te (W c,,) , Btu/ (hr F) [Wr C] 

### c., S p ec ifi c he at a t co nsta nt press ure , Btu/ (lb ", F ) [kj l kg· " C] e B ase of natura l logarithm LMTD L og mean te mp e rature differe nce , F (0 C] 

### Nlit N umb er of ex c hanger heat tran s f e r unit s q Total he at transferred , Btulh

. 

## IWJ R T o tal t h e rmal res i s tan ce , hr s q fl F I Btu [ m l

. O O W] 3

### ARI STANDAR D 470-87

_
Table 1. Standard Rating Conditions Saturated Actual Type Temperature Temperature Temperature Temperature of Entering of Entering of Entering of Leaving System Refrigerant Refrigerant Water Water Vapor Vapor F °C F °C F °C F °C Air cooled 125 51.7 220 104.4 90 and 120 32.2 and 48.2 140 60 Water cooled lOS 40.6 180 82.2 90 and 120 32.2 and 48.2 140 60

r Individual thermal resistance term, hr sq ft 

### FlBtu [m 2 ·°c/W] t Temperature, F [0C] U Overall heat transfer coefficient, Btulh sq ft F [W/m 2 

### .oCl W Mass flow rate, Ibm/hr. [kg/s] E Exchanger heat transfer effectiveness 

### Subscripts
c Cleaned e Entering f Fouled or fouling I Inside 

# e Leaving o Outside r Refrigerant w Water
5.5 

### Tolerances. To comply with this standard, published heat exchange effect shall be based on data obtained in accordance with the provisions of this section, and shall be such that any production unit selected at random and tested in accordance with this section will have a useful heat exchange effect not less than 95 per cent of the published rating, a water pressure drop not more than 110 per cent of the published water pressure drop and a refrigerant pressure drop not more than 110 percent of the published refrigerant pressure drop.

4 

### Section 6. Safety Recommendations and Sanitary Provisions 

### 6.1 Safety Recommendations. It is strongly recommended that the product be designed, constructed, assembled and installed in accordance with nationally recognized safety standards and codes appropriate for the product covered by this standard. 

### 6.2 Sanitary Provisions. Certain jurisdictions may require provisions to preclude possible potable water contamination by refrigerant. 

### Section 7. Marking 7.1 Each desuperheater/water heater shall have the following minimum information shown in a conspicuous place:
a. Name of manufacturer b. Manufacturer's model number c. Design working pressure for the water side d. Design working pressure for the refrigerant side 

### Section 8. Voluntary Conformance 

### 8.1 Conformance. While conformance with this standard is completely 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. 

### ARI ST AN D A RD 4 7 0 -8 7

____ _ __________________ _

T a b le 1. Sta nd ard R atin g Cond itio n s Sat ur ated AClUal T y p" T emperature T e mperature System of Entering of Emer l ng R ef rigerant Refrig e rant

r Vapor F 

## · c Air cooled 115 5 1.7 Walcrcookd 105 40 .6

Individual thermal res is tan ce term , hr sq 

### ft F/ Btu [ m I

. DO W] 

### T e mp erature , F [0C] Vapor F 220 180

t U 

### Overa ll hea t transfer coefficient, Btulh sq ft 

### F [W / m l

. G C] 

## w 

# , Ma ss fl ow rate , lbm/hr. 

### I kg/sJ Exc han ger h eat transfer effec ti veness

c C lea n ed e E nt e rin g f Fou l ed o r fouling 

### i I ns ide { Leaving o Outside r Refrigerant w Water S ub sc r i p ts



### 5.5 Tolerances

. To co m p ly wit h thi s standa rd. pub

li s hed hea t exc han ge ef f ect s h a ll b e base d o n data ob

tained in accordanc e with th c provisions o f this sec t ion. a nd s hall be s u c h th a t any pmdu c ti o n unit se lected 111 rand om a n d tes te d in acco rd ance with thi s sec ti o n will hav e a use ful heat exchange effect n o t lcss than 95 per cent of the pub lished rating , a wate r pres s ure d ro p not more than 110 pe r ce n t of the publi s hed wa te r prl!ssure drop an d a refrigeran t p ress ure drop not more than 110 percent of th e p ublished re fr igerant pressure d rop.

4 

### ' C 104.4 82

. 2 T e mperature Temperature of Emcrin g of lA:avin g

Water Water

F 

### ·C F 

### · C 90 an d 120 32.2 and 48.2 14O 60 90 and 120 32.2 and 48.2 140 6 0

Sec t io n 6 , Safety Recommend ati ons an d Sani ta ry P r ovi si ons 

### 6.1 Safe t y R ecommendatio ns . It is s tron g ly reco mmended t h at the pro du ct be designed, co n s tru cted , as se mb le d a nd in s tall ed in accordance with nati o nall y recog ni ze d safe t y s ta nd ard s a nd codes appropriate for the pro du c t covered b y this sta nd a rd. 

### 6.2 Sanitary Prov isions. Certain jurisdictions may req u ire pro vi sion s to pre clud e possible potab le water co n tamination by refrige rant.
Sec ti on 7

. M a rkin g 7.1 Each d cs u pe rh e at e r/ watc r h eater s ha ll ha ve the followin g minim um info r ma ti o n s hown in a conspicuous place:
a. Nam e of manufacturer b. Manufac turer's mo del num be r c . De si g n working pre ss ure f o r the water side d. Design workin g pressure for th e refrigerant s id e S e ction 8. V o luntary Conforma n c e 

### 8.1 Confo rman ce. While conformance with thi s s tan

d a rd i s co mpl e t e ly vo luntary, co nform ance shall not b e cl a imed or implied f o r produ cts or equ ipme nt within its 

### Purpose (Sec tion 

### I.) a n d 

### Scope (Sect ion 2 .) unl ess s uc h claim s m ee t a U of th e requirements of th e Standard

._______________________ ARI STAN DARD 470-87

APPENDIX A. METHOD OF TESTING DESUPERHEATER/WATER HEATERS

Section A 1. Purpose 

### AI.I Purpose. This appendix prescribes methods of testing for rating desuperheater/water heaters. Section A2. Scope A2.1 

### Scope. This appendix applies to desuperheater/ water heaters supplied as a separate component. Section A3. Definitions A3.1 

### Desuperheater/Water Hearer. A factory-made assembly of elements by which the flows of refrigerant vapor and water are maintained in such a heat transfer relationship that the refrigerant vapor is desuperheated and the water is heated. A3.2 

### Useful Heat Exchanger Effect. The useful heat transferred shall be the product of the mass flow of water, the specific heat and the temperature difference between entering and leaving water. A3.3 

### Total Heat Exchange Effect. The total heat removed from the refrigerant in the heat exchanger. This is the sum of the useful heat exchange effect and the heat loss through the external surfaces of the heat exchanger to the ambient air. A3.4 

### Nominal Refrigeration System Capacity. The cooling effect produced shall be the product of the refrigerant mass flow of refrigerant and the difference in enthalpy between the refrigerant entering the evaporator and the refrigerant leaving the evaporator. Section A4. Expression of Test Results A4.1 

### Terms Recommended for Expressing Test ResuIts. A4.t.l Test results shall be expressed in the following terms:
a. The useful heat transfer effect, Btuh [W) b. Temperature of entering water, F rOC) c. Temperature of leaving water, F rOC) d. Temperature of entering vapor, F rOC] e. Water flow rate, gpm 

### [Us] f. Refrigerant mass flow rate, lbs/hr [kg/s] g. Water pressure drop through heat exchange, psi [kPa] h. Vapor pressure drop through heat exchanger, psi [kPa] I. Pressure of vapor entering heat exchanger, psig [kPa] j. Refrigerant designation Section AS. Test Methods A5.1 

### Standard Test Methods. A5.1.1 Tests shall consist of measurement of the following at specified conditions:
a. Temperature of entering and leaving water, 

### F [0C] b. Temperature of entering and leaving vapor, F [0C] c. Pressure of entering vapor, psig [kPa] d. Water pressure drop through heat exchanger, psi [kPa) e. Vapor pressure drop through heat exchanger, psi [kPa] f. Water flow rate, gpm {Us] g. Refrigerant mass flow rate, Ib/hr Ikgls] (measured on liquid side) h. Ambient temperature, F [0C] A5.t.2 The total heat transfer effect shall be determined by:

a. Multiplying the mass flow rate of water by the specific heat and temperature difference between entering and leaving water (useful heat transfer effect) and adding to this the heat lost by the refrigerant vapor through the external surfaces of the heat exchanger (see 

### A5.1.6). b. Multiplying the refrigerant mass flow rate by the enthalpy differences between entering and leaving refrigerant. A heat balance calculated between a and b shall be within ± 5%. A5.t.3 The water flow rate shall be determined in accordance with 

### A6.4.1. A5.t.4 Rate of refrigerant flow shall be determined in accordance with 

### A6.4.2. A5.t.5 The enthalpy difference between the entering and leaving refrigerant shall be determined from temperature and pressure measurements and the applicable thermodynamic properties of the refrigerant. A5.1.6 The heat lost through the external surfaces of the heat exchanger to the ambient air shall be determined by: All t,1l**q=~** 

### 5 ARI STANDARD 470-87
APPENDIX A

. METHOD OF TESTING DESUPERHEATER / WATER HEATERS

Section A 1. Purpose At.l 

### Purpos e. Th is append ix presc rib es me thod s of test i ng for rating desupcrheatc r / wate r h eaters. 

### Section A2

. Scope A2.1 

### Scope

. This appendix a ppli es to d esupe rh e at e r l water h ea te rs s uppli ed as a sepa rate co mpon e nt. Section A3

. Definition s A3. 1 Desuperheorerl Waler H eate r . A faewr y- made asse mbl y o f e lem en ts by which th e flow s of refr ige ran t vapor and wa ter are ma in tain ed in s uch a h e al t ran s f e r rcia t ion s hi p th a I the re fr ige rant va por is dcsupcrhcatcd a n d the water is hea ted. A3.2 

### Useful H eal Exc han ger Effeci. Th e u se fu l h eal tran s f e rred shall be th e produc t o f the ma ss flow of wa ter , th e spec ific hea l an d th e temperatu re d iffere n ce b e tw een e ntering and le avin g water. A3.3 

### T o tal Heat Exchange Eff ect
. The tolal h eat remove d from t h e refri ge ran l in the hea l exchanger

. Thi s is the s um of th e us e fu l heat exc hang e e ff ec t a nd the heat lo ss throu g h the ex t e rn al s urf aces of the heat exc h a n ge r to t h e ambient a ir

. A3.4 

### Nom inal Refrigeration System Capacity. Th e coo li ng effect produced s h a ll be th e produ ct of th e refrigerant ma ss fl ow of r e fri ge r a nt and th e difference in e nthalpy between the refrigerant e nt e r in g th e evaporat or a n d th e refr ige rant leavi n g t he eva p o ra to r. Section A4

. Expression of Test Results A4.1 

### Terms R ecomme nded for Ex pressing Tes t R e

### s ult s. A4.t.l T est res ult s s hall be e xpre ssed in th e foll o wing te r m s: a . The u se ful heal tr ans fer e ffect

. Btu h [ W ] b. Temperature of e nt e ri ng water , 

### F (O C l c. T e m perature of le a vi ng wate r , 

### F r O C] d

. T e mperature of e nt erin g va p or. F 

### [O Cl e. Water How r ate , gp m (Us ] f. Ref ri gera nt ma ss flow rate , I bslhr [kg/s ] g. Water p ressu re drop th rough h ea t exc h ange. p s i IkPa] h

. Vapor pr ess u r e d r op thr ough h ea t exc h ang e r , p s i [kP a] I. Pre ss u re o f vapo r e nt e r i ng h ea t exc h a n ge r , p sig [k Pa ] j. Refrigerant de s igna tion Section AS

. Test Methods 

### AS

. ! 

### Standard Test M e th ods. AS.l.l T es t s s ha ll co ns ist o f meas ure ment o f the follow in g at spec if ied co nditi o n s:
a . Tempe rature of e nt e ring a n d leaving water. F [0 C] b

. T e mp erature o f e ntering and leav in g va por . 

### F loC I c. Press u re of e nt e rin g vapo r . ps ig [kPa ] d

. Wat e r p r ess ure dr o p th r o ugh h eat exc han ge r , p s i [k PaJ e . Vapor pr ess ur e drop throu gh h eat exc h ang e r , p s i lk P aj f. Water fl ow ra te , gpm [Us ] g . Refri ge rant ma ss fl ow rate. Ibl h r [ kg/sl (meas ured on liquid s ide) h

. Amb ie nt te m pe rature , 

### F r o C] 

### AS.t.2 Th e total heat tran s fer effecl s ha ll be de

te r mined b y:

a . Multip lyi ng the ma ss fl ow r ate of wate r by the speci f ic h ea t a nd temp e rature differe nce between e n ter in g and leaving water ( usef ul h e al tran s f e r effec t ) and addin g to thi s th e heat los t b y t h e re fri ge rant vapor throu g h th e exte rnal s urfaces of the h eat exc han ger (see AS. 1.6 ). b

. Mu lt iplyi ng the refrige ra n t mass How rat e by the entha lp y di ffe re n ces b e tw ee n e n tering and leav in g ref ri gerant. A h ea t balance calculated between a a n d b s h a ll 

### be with in ± 

### 5%. AS.1.3 The waler flow rate s ha ll be determin e d 

### in a cco rd ance with A6.4

. 1

. 

### AS .1.4 Ra te of ref r ig e ra nt fl ow s hall be det erm i ned in acco rdan ce with A6.4 .2. AS.1.S The ent halp y differe nce between th e e n te rin g a nd le av i n g re frigerant s ha ll be d e te rm in e d f rom te mp e ratu re an d pressure m easur eme n ts a nd t he app lic a bl e ther mo d y n am i c properties of th e re frig e rant
. AS. l .6 Th e h eat lo st th rough the ex terna l s ur faces o f t h e h eat exc h anger to th e a mbient a ir s h a ll be dete rm ined by: A6<". q**-R** 

### S

### ARI STAN DARD 470-87

_ Where: q heat loss through external surfaces, Btu/h 

### [W] A external surface area, sq ft [m 2 ] Li t", 

### log mean temperature difference, F [0C] 

### (calculated between entering and leaving refrigerant temperature and the average ambient air temperature)


### x 1 R = - 

### + - hr ftl F/Btu [m 2 • 

### °C/W] k h s ' 

### Where:
x = 

### insulation thickness, ft [m] k thermal conductivity of insulation, Btu/h 

### ft F [W/m .0C] h s = 

### surface film coefficient 2 Btu/h ft 2 

### F [11.36 

### W/m 2 • 

### 0c] A5.1.7 The heat absorbed by the water is the product of the mass flow, the specific heat and the temperature difference between entering and leaving water. A5.I.S The heat rejected from the refrigerant is the product of the refrigerant mass flow rate and the enthalpy difference between the refrigerant entering and leaving the desuperheater.
Section AG. Instruments, Test Apparatus, and Thermodynamic Properties 

### A6.1 General. A6.1.1 Instruments, whose types and accuracies are listed below, shall be calibrated against standards before and after each test. A6.2 Temperature Measuring Instruments. A6.2.1 Temperature measurements shall be made in accordance with ASHRAE Standard 41.1-74. 

### A6.3 Pressure Measuring Instruments. A6.3.1 All pressure measuring instruments shall have an accuracy within the limits of ± 

### 1 % 

### of the absolute pressure readings or ± 

### 2% of the differential pressure readings. A6.4 Flow Measuring Instruments. A6.4.1 Water Flow Measuring Instruments. A6.4.1.1 Accuracy of flow meter shall be within ± 

### 2% within the range of flows measured. 

### 6 A6.4.2 Refrigerant Flow Measuring Instruments A6.4.2.1 Direct volume flow measurement shall be made with one or more of the following instruments:
a. Liquid refrigerant quantity meter b. Liquid refrigerant flow meter c. Gaseous refrigerant flow meter A6.4.2.2 A refrigerant calorimeter may also be used for indirect measurement of the refrigerant flow. In this approach, the calorimeter is used to accurately measure the amount of heat required to evaporate and superheat the refrigerant flowing through it. The rate of refrigerant flow is determined by dividing the heat input, including leakage losses, by the enthalpy difference between the entering and leaving refrigerant. A6.4.2.3 Accuracy of either the direct or indirect refrigerant flow measurement shall be within ± 

### 2% within the range of flows measured. A6.4.2.4 Instruments shall be applied and used in accordance with AS ME PTC 19.5.3 and 19.5.4. A6.4.3 Thermodynamic Properties of Refrigerants. Thermodynamic properties of refrigerants shall be obtained from the current issue of the ASH RAE Refrigerant Tables, Charts and Characteristics (American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.). Section A7. Test Procedure 

### A7.1 General. A 7.1.1 The desuperheater/water heater, the selected instruments, and test apparatus are assembled, connected, tested, dehydrated, evacuated, and charged with refrigerant. If 

### necessary, a refrigerant superheater may be used, to assure accuracy of measurements and to obtain specified conditions. A 7.1.2 The water side surfaces of the heat exchangers should be cleaned immediately prior to the test. This method gives cleaned-tube test results. A7 .1.3 The refrigerant system should be checked for non-condensables. Non-condensables present for a test intended for rating should not exceed that amount which increases the condenser pressure more than the equivalent of 0.5 F [0.3°C]. A 7.2 Operation and Limits. A 7.2.1 Start the system and obtain and maintain the specified conditions in accordance with the following tolerances: ARI STANDARD 470-87

_______________________ _
Wh e r e: q = heat lo ss through external surfaces, BtU/h 

### [W] A = eXlernal s urfa ce area, s q fl [ mIl 6 I ", = log mea n le mp e ralUre differe nce, F 

### rO C] (calculated between entering and l eavi ng refrig e rant temperature and Ihe averag e am bie nt air temperature )

, I 

### - + - hr ft l F /Bm 1m ! ' °C/ W I k 

### h, ' R**~** Wher e:
x = in s ulation thickn ess, ft [m1 k = thermal conductivity of insulation , Btulh ft F [W / m . 0 C) 

### h. = s urf ace film coefficient = 2 Btu / h ft 

### 2 F 111 .3 6 W/ m 2 • 

### 0 c] AS.I.7 The h e al absorbed by the wat e r is th e product of th e ma ss flow , the spec ifi c heat a nd the te mp e rature difference between e nt e rin g and leaving water. 

### AS.I.S The hea t re j ec ted f ro m the r e frig e rant is the product of the refrig e rant ma ss flow Tal C and the e nthalp y difference b e tween th e ref rigerant e n tering and leaving the de s uperheater

.
Section A6. Instruments, Test Apparatus , and Thermodynamic Properties A6.1 

### General. A6.1.1 In s trum e nt s, whose ty pe s a nd accuracies are li s te d below , s hall be ca librated agains t s ta n dards b efo re and after eac h test. A6.2 

### T emperatu re Measuring In struments
. A6.2.1 Temperature me as urem e nt s s hall be mad e in accordance with ASH RAE Sta ndard 4 1.1 -7 4

. A6.3 

### Pressure Mea suring In strum enls

. A6.3.1 All pressure mea s uring instruments s hall have an accurac y within the limits of ± 1 % of the absolute pre ss ure reading s or ± 2 % of the differ

ential press ure reading s. A6.4 

### Flow Mea suring Instrum enlS.



### 6 A6.4.1 

### War e r Fl ow M eas uring In slruments

. A6.4.1.1 Accuracy of flow meter s hall be withio ± 2 % within the rang e of flow s mea s ured. A6.4.2 

### Refrigeranl Flow Measurin g In Sl ruments A6.4.2.1 Direct vo lum e flow measurement s h a ll b e mad e wit h o n e or more of th e followin g in s trum e n ts:
a. Liquid refri ge rant quantity met er b

. Liquid refrigerant flow m e ter c . Gaseous refri ge rant flow m ete r A6.4.2.2 A re frig e ran t ca lorimet e r ma y a lso be u se d for indirec t me as urem e nt of th e Tefrig

era tli flow. In thi s approach , the ca lorimeter is u sed t o accurately mea s ure the a mount of he at required t o eva porate an d s uperh ea t the r ef

ri ge rant flowin g throu gh it. The rat e of ref r igerant fl ow is determined by dividing the heat in

put
. including lea kag e losses, b y the e nthalp y difference between the en te ring and leaving refri ge rant. A6.4.2.3 Accuracy of either the dire ct or indir ec t refrig e rant How measurement s hall be wit hin ± 2% within th e range of flows mea s ured

. A6.4.2.4 In s trum e nt s s hall b e applied and u sed in accordance with ASME PTe 19.5.3 and 19.5.4

. A6.4.3 

### Thermodynamic Pr oper/ies of Refrig e rants. Thermodynamic properti es of refrig e ran ts s hall be o btain e d from the c urrent iss ue of the ASH RA E 

### Refrig era nt Tables, Chart s and Characleris/ics (Ame ri ca n Society o f H ea ting , Refrig e ratin g and Air-Conditioning Engineers, In c.)

. Section A7. Test Procedure A 7.1 

### Ge l/eral. A7.t.1 Th e desuperheater ! w at er heat e r , the se lec t ed instrum e nt s, and test apparatus are asse mbl ed, connec t ed, t es t ed. de h yd rat ed , evac uat ed , and c harged with re fri ge ra nt. If ne cessa ry. a refrige rant s up er hea t e r may be use d , to a ss ure accur acy of measurements and to obtain spe cifi ed co nditi o n s. A 7.1.2 Th e water s ide s urfa ces of the he at exc h a ng er s s hould be cl e an ed imm edia t e ly prior to the test. Thi s me tho d g ive s cl ea ne d

- tube test results. A 7.1.3 The refri gera nt syste m s hould b e c hec ked fo r n o n- con d e n sab les. Non-condensables prese nt for a test intended f o r r ating s hould n o t exceed that a mount whi c h i nc r eases th e co nd e ns e r press ure more than the eq uiv a le n t of 0.5 F [O

. 3"C). A7.2 

### Operation and Limits. A 7 .2.1 Start th e sys te m a nd ob tain and mai ntain t he s pe c ifi ed conditions in accordance with the following tolerances:

### _______________________ ARI STANDARD 470-87

a. The arithmetic average of pressure readings used to determine refrigerant enthalpies and refrigerant saturated temperatures shall not vary from the required values, by more than 2.0% of their absolute values, nor shall the individual pressure readings vary by more than this amount from the average value. Pressure readings shall be converted to absolute values to determine refrigerant saturated temperatures. b. The arithmetic average of temperature readings of water and vapor entering and leaving the desuperheater/water heater shall not vary from the specified value by more than 1.0 F [O.6°C] nor shall the individual readings vary by more than this amount from the average value. A 

### 7.2.2 After establishment of steady flow conditions, all required readings shall be taken at intervals of not less than fifteen minutes, and the test shall be continued until two consecutive sets of readings are within the specified limits. 

### A 7.2.3 The test re<:ord shall include the date, observers' names, essential identifying physical data of the desuperheater/water heater tested, refrigerant used, all test readings, reference to instrument calibrations and computations, and the determined results.

Section A8. Computation of Results 

### AS.1 The useful heat exchan,ger effect, q, is by definition the heat gained by the water and is the product of the mass flow of the water, the specific heat and the. temperature difference of the water. q = we"dt = [1000 w e"llt] Where:

w Mass flow rate, lbs/hr [kg/s] Cp Specific heat of the water, Btu/lbF [kJ/kgOC] Il t Temperature difference between the entering and leaving water, F [0C] q Heat transferred, Btu/h [W]



### 7 

### ____ ___________ _____ _ ___ ARI STANDARD 470
- 87

a. Th e a rithm e ti c ave rage of press ure re a di n gs u sed to dete rmin e re fri ge rant e nl halpi es a n d re fri ge r a nt sa tur a ted te mper a tures s h a ll nO I va r y fr o m th e req uire d valu es, b y mo rc th a n 

### 2.0% o f 

### th c iT a b so lu te va lues, no r shall th e in d ividu a l press ure readi ngs vary by 

### mo rc than t h is a mo unt f ro m Ihe ave ra ge va lu e. 

### Press ure readings s h all be 

### co nve rte d t o absolut e va lu es 1 0 de te rm in e refri ge rant sa tu

- rat ed t e mp e r atur es. 

### b

. Th e a rithme t ic average of t e mp e r ature read

in gs o f wa t e r a nd vapo r e nterin g a nd leavi ng Ih c d cs upe rh ea tc r / w3 tc r he al e r s hall nO I va ry fr o m th e s pecifi ed valu e b y more Ihan 1.0 F [ O.6°C] no r s hall th c individual re adin gs va ry by mo r e th an thi s am o unt from t he a v

### e r age va lu c . A 7 .2.2 Aft e r e stabli s hm e nt of stead y H ow con · diti o ns, a ll rcquire d re adi ngs s h all be take n at in · tc r va ls o f no t I css tha n fift ee n minute s, and the tes t sh a ll 

### be co nt inu e d until two co n sec uti ve se t s of readin gs a re within th e spec ifi e d limit s. A 7

. 2

. 3 Th c tes t reco rd s hall inclu de th e d a te , o b se rve rs' n a mes, essen tia l id e ntif y in g p hysical d ata of th e des uper heate r / wat e r he at er teste d

. re· fri ge r a nt used, all les t read ing s , re f e re nce to in· stru me nt ca li b r a ti o ns a nd co mputa t io n s , a nd th e deter min ed res ults

.

Sect i on A8

. Computation of 

### Re s ults AS. 1 Th e u se ful heat exc han ger eff ec t , q . is b y de fin i· tio n th e heat ga in ed b y th e wa t e r and is th e prod uc t o f th e ma ss fl o w o f th e wa te r , t he spe cifi c he at a nd th e . te mper a ture diff ere nce o f th e wa ter. q ::: 

### wc.. At '" [IOOOwc" At J Whe re:

W : 

### Ma ss flow ra te, lb s/hr [k g/s ]



# .. : 

### S p eci fi c he al of th e wa ter, Bl ul lbF [k J/ kg °C] 

# " , : 

### T e mpe r at ure d iff e renc e be tw ee n th e e nteri n g a n d leav in g wa le r , F [0C] q : 

### Heat tr a n s f e rre d , Btuth (W]



### 7