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REFRI DATION

AIR CON ~N IONING

3rd Edition

Hipolito B. Sta. Maria

{(dimu;i Book Store QUAD ALPHA CENTRUM BLDG. 125 Pioneer s... Mandaluyong City

.l...

Contents

!'//!I!ishcd b»

r(dimtd

Book Store

Preface

VB

Chapter

1

PHILIPPINE COPYRIGHT, /I.)X9, 2001 bv Hipolito B. si« Mario

2

Third Editioll, 2001

Refrigerating Machine and

Reversed Carnot Cycle,

.

Simple Vapor Compression

Refrigeration Systems

1

12

3

Actual Vapor Compression Cycle

4

Multipressure Systems

5

Cascade Systems

6

Air-Cycle Refrigeration

7

Steam-Jet Refrigeration

8

Air Conditioning

9

Cooling Tower................................................ 154

.

57

)

1

, ( I

All rights reserved. No part of this book may be

reproduced in anvjorm or by an\' meall.\', except brief quotations

review. without permission in writing [rom the Author.

{or

II

Printed II\'

Kaluvaun /'/(\\ .'Ilktg. Ell!.. 1.)6 Kalavaan St., l iilnnau

Q//I':OI/ ( '1/ v

""-.

10

Drying

11

Product Load

. .

90

.................................

98

.

107

.

113

,.

'" '"

78

'"

'"

166

II/C.

ISBN 971-08-6/72-7

181

-Preface

This book has a two-fold purpose: to serve primarily as a college text and as a reference material for the practicing engineer. The author attempts to present refrigeration and air conditioning in the simplest possible way without sacrificing quality. Principles and concepts are discussed thoroughly using mostly basic thermodynamics, followed by illustrative problems arranged in the order of increasing difficulty. Additional exercises are also provided at the end of each chapter to further enhance the learning process. Answers are given to all the problems so that the student himself can check the accuracy of his solutions. For the student to get the most from this book, he should solve all the problems at the end of each chapter conscientiously. This is the best way to study and learn any technical subject.

)

1,

The Author

....

~

--Chapter

1

Refrigerating Machine and Reversed Carnot Cycle SI units SI or the International System of Units is the purest form and an extension and refinement of the traditional metric system. )

1 l

Unit of Force The unit of force in the SI system is the newton, denoted by the symbol N. 1 kg f = 9.8066 N 1 lb f = 4.4484 N 1 lb, = 0.4536 kgf

Unit of Pressure The SI unit of pressure is the pascal and is denoted by the symbol Pa. 1 Pa

= 1 Nzm"

1 bar = 100 kPa 1 psi = 6895 Pa 1 atm =.101.325 kPa = 1.033 kg/em" = 14.696 lb zin"

........

2 Refrigeration and Air Conditioning

Refrigerating Machine and Reversed Carnot Cycle 3

Unit of Energy and Work

Heat Engine and Refrigerating Machine

The SI unit of work is the newton meter denoted by Nm or joule denoted by J.

A system operating in a cycle and producing a net quantity of work from a supply of heat is called a heat engine and is represented as shown in Fig. 1-1.

1 Nm = 1 J

1 cal

= 4.187 J

Hot reservoir (source of heat)

1 Btu = 252 cal = 1055 J ~

Unit of Power

@-+W

The SI uni t of power is the watt, denoted by the symbol W. It is defined as tho rate of doing 1 Nm of work per second. 1W

= 1 ,Us

1 hp

=

1~

0.746 kW

= 4~.4

~

Btu/min

Unit of Refrigerating Capacity

Cold reservoir (receiver of heat)

Fig. 1-1. Representation of a heat engine The standard unit of refrigeration is ton of refrigeration or simply ton denoted by the symbol TR.

W

=.

QA

One ton of refrigeration is the rate of cooling required to freeze one ton of water at 32°F into ice at 32°F in one day.

e

=

Q

In English units

where

1 TR = (2000 lb) (144 Btu/lb) 24 h 1 TR

= 12,000 Btu/h = 200 Btu/min

In Metric units

-

QR

W _ QA - QR QA A

QA

= the heat supplied

QR

= the heat rejected

W

= the net work

e

= the thermal efficiency

1 TR = (12,000 Btulh) (252 callBtu) 1 TR = 3024 kcallh

=.

50.4 kcallmin

In Sl units 1 Tl{

= (200

Btu/rnin.) (1055 J/Btu)

I TH = ~11 k.L'min = 3.52 kW

~

A refrigerating machine will either cool or maintain a body at a temperature below that of its surroundings. A refrigerating machine may be represented by the diagram shown in Fig. 1-2. The machine R absorbs heat QA from the cold body at temperature T 1 and rejects heat QR to the surroundings at temperature T 2 and, during the process, requires work W to be done on the system.

4

Refrigeration and Air Conditioning

Refrigerating Machine and Reversed Carnot Cycle ;)

T2

surroundings

The Carnot power cycle consists of the following reversible processes: process a-b: isothermal expansion, 1'" = T = 1'] b process b-e: isentropic expansion, SI> = S, process c-d: isothermal compression, T = T = T, c

~

ri

process d-a: isentropic compression, Sri = S, cold

body Fig. 1-2.

\{l"prl"~entation of

QA

cOP =

----w- =

where

QA

W = QA

QA

Q,,_.Q

,

= the heat absorbed from the cold body or

The performance of a heat engine is expressed by its thermal efficiency. The performance of a refrigerating m achin e is expressed by the ratio of useful result to work, called energy ratio or coefficient of performance (COPl.

T

e

e

_ 1'] ~ T.

T

]

where

Q A = the heat added by the hot body

1']

= the heat rejected to the cold body

c y

s

('arnot Cyril'

= the thermal efficiency

= the temperature of the Source of heat

T 2 = the temperature of the sink or receiver of heat

d

I·:l

,"I

(1'1 - 1',,) ISh - S) r 1 (SSa )

'b

= W

Q

e

'CJ~ l'li~

:!'!,

1

W = the work done

a

....

= (1' _. T ) (S - S )

QR

The Carnot Cycle p'

QR

-

= 1'\ (S" - S) - 1'2 (SI> - S)

!\

refrigeration produced QR = the heat rojected to the surroundings W = the work done or mechanical energy consumed COP = the coefficient of performance

1

.s, - Sa)

= 1'"

1\

)

.s, - S)

1'1

QR = 1'2 (S,--S)

a refrigerating machine

W == Qi( -- Q\

Q\

=:

6

Refngeration and Air Conditioning

Refrigerating Machine and Reversed Carnot Cycle 7

The Reversed Carnot Cycle

where

T

p c

T=:~r a

F'i~.

s /{"v('r'sed Carnot Cycle

I ·1.

= the heat absorbed from

QR

:::

W

= work done

the cold body

the heat rejected to the hot body

COP= the coefficient of performance

d

v

QA

The reversed Carnot cvcl« follows the same processes as in the power producing Carnot cycle, but the cycle operates in the counterclockwise or reverse direction. The reversed Carnot cycle consists of the followi ng pn)('('ss('s:

T[

= the refrigeration temperature

T2

= the temperature of heat rejection to the surroundings

(1-1) A refrigerating system operates on the reversed Carnot cycle. The higher temperature of the refrigerant in the system is 120°F and the lower is lOoF. The capacity is 20 tons. Neglect losses. Determine: (a) Coefficient of performance. (b) Heat rejected from the system in Btu/min. (c) Net work in Btu/min. (d) Horsepower,

SOLUTION

process a-b: isentropic compression, Sa == Sh T

process b-e: isothermal heat rejection, T h ::: T, ::: T 2 process c-d: isentropic expansion, Se = Sa process d-a: isothermal heat absorption, T d == T, == T, Q A =Tj(Sa- S) Q R == T 2

e

dJ

rs, - S)

~R

..

470 0 R

b

T'. = 10 + 460 = 470

,.

T,

QA::: 20 TR

==T2 (Sa - S a)

W = QR - QA

B

= T 2(Sa - Sri) - T[ ($a - So)

= (T

Til (Sa - Sdl

-

2

COP = Q A

:::

W

--..

COP

=

(T 2

T) T~ - T[

TI(Sa-Sa) - T I) (Sa- Sa)

= 120 + 460 :::

0R

580

0R

Refrigerating Machine and Reversed Carnot Cycle 9

1;,1'11"'1;1111111 .u u] .\11' (1III1iJll.lllIllg

T I T! - T

( :I I

CO!' "

(b)

COP=~

=

470 ::i80 - 470

= 4.273

.1)

COP

W

=

COP

=

(:20) (200) 4,273

= 936

Btu/min.

QR = W + Q\ = 9:l6 + 4000 == 4936 Btu/min, (c)

W W

=

936 42.4

= :2:208 hp

(1-2) A refrigNation system operates on the reversed Carnot cycle. The minimum and maximum temperatures are minus 25 cC and plus 72 C. respectively. If the heat rejected at the condenser is 6000 k.l/rn in , draw the TS diagram and find, (a) power input required. n nd (b) tons of refrigeration developed. SOLUTION T

:Cjb

T] = -25 + 273 T,~ =

s

....

= 248

K

72 + 273 = 345 K

QR = 6000 kJ/min

a

~

-

248

345 - 248 = 2.557

j

T.

A = QW --~Q Q A

(~~

_ (COP) (QR) 1 + COP

W

=

{\ ~A

=- = 20 .44 211

= 936 Btu/rn in. , hi

(d)

T2

R

Q,\

W

T

COP

(2.557) (6000) = 4313kJ/min. 1 + 2.557

QR - QA = 6000 - 4313 = 1684 kJ/min. 4313

TR

Refrigerating Machine and Reversed Carnot Cycle 11

10 Refrigeration and Air Conditioning

PROBLEMS

(1-3) The power requirement of a Carnot refrigerator in maintaining a low temperature region at 238.9 K is 1.1 kW per ton. Find (a) COP, (b) Te;' and (c) the heat rejected.

(1) A reversed Carnot cycle is used for refrigeration and rejects 1,000 kW of heat at 340 K while receiving heat at 250 K. Determine (a) COP, (b) the power required, and (c) the refrigerating effect.

SOLUTION

Ans. (a) 2.778, (b) 264.7 kW (c) 735.3 kW

T

CQb

'. '1\

II!

T[ = 238.9 K

·238.9K

d

a

,/ (2) A reversed Carnot cycle has a refrigerating COP of 4. (a) What is the ratio Tmax/Tmin? (b) If the work input is 6 kW, what will be the maximum refrigerating effect, kJ/min and tons.

W = 1.1 kW/TR Ans. (a) 1.25,

QA

~ 1 T R or 3.52 kW

W

=1.1kW

Ans. 9230.7 kW

QA 3.52 kW =3.2 COP = W = 1.1 kW (b)

T[ COP = T - T 2

3.2

j

238.9 - T l-238.9

T 2 = 313.6K (c) Q n

~

= W + Q A = 1.1 + 3.52

6.82 TR

'(3) A reversed Carnot engine removes 40,000 kW from a heat sink. The temperature of the heat sink is 260 K and the temperature of the heat reservoir is 320 K. Determine the power required of the engine.

s

(a)

(b)

:=

4.62 kJ/s

I

/ Simple Vapor Compression Refrigeration System 13

Chapter

2

The pressure-enthalpy (ph) diagram and the temperature entropy (T's) diagram are the diagrams frequently used in refrigeration cycle analysis. Of the two, the ph diagram is the one most commonly used. The process which comprise the standard vapor-compression cycle are:

Simple Vapor Compression Refrigeration Systems

1-2, reversible and adiabatic compression from saturated vapor to the condenser pressure 2-3, reversible rejection of heat at constant pressure de superheating and condensation 3-4, irreversible expansion at constant enthalpy from saturated liquid to the evaporator pressure 4-1, reversible addition of heat at constant pressure in evaporation to saturated vapor

III

Refrigeration is that branch of science which deals with the process of reducing and maintaining the temperature of a space or material below the temperature of the surroundings. Refrigerant is the working substance in a refrigeration system.

, }

: I

l

Condenser

~

2 •

:=L

Analysis of the Vapor Compression Cycle 1.

Compressor

·.~w -1Jw-~

Expansion valve

J

~

w

2

ell

1:1

.::s

.S

~I

r.:l

oj

'"'"

.~~

~.1

;'"

Q,

l<

Evaporation

6'J$'

:.::

e::s

e8­ 8

~I

/

4

:2.

CondeI1i\er

Entropy, kJtq K

Fig 2-2. The p-h and T-s diagrams of standard vapor compression cycle

q, q,

=h =.

2 -

/Q

CIc

L / ' ~n,

".-{: Enthalpy, kJlkg

=

W m(h2 - hI) VI = mVI w ::: work of compression, kJ/kg h, ::: enthalpy entering the compressor, kJlkg h, ::: enthalpy leaving the compressor, kJlkg m ::: mass flow rate, kg/s W ::: theoretical compressor power, kJ/s or kW v l ::: specific volume of vapor, m 3/kg or Llkg VI::: volume flow rate, m 3/s or Lis

Fig. 2-1. Vapor compression refrigeration system

~

=h2-h i

h,

he at r'ejr-ct.ed , k.Jlkg

rl

--=

Qc ::: mrh 2-h) 3

c

~m

14 Refrigeration and Air Conditioning

Simple Vapor Compression Refrigeration System 15

h,

=

h,

= enthalpy leaving the condenser, kJlkg

Qc

= total heat

3.

enthalpy entering the condenser, kJlkg

:). Coefficient of Performance (COP) The coefficient of performance is the ratio of the refrigerating «ffect to the work of compression.

rejected, kJ/s

Expansion valve

COp= h. - h, h, - h.

hI

(.;.

11

Efficiency ,

~

Y = ~ = D2LN 11 4

hg::14

, J

4.

h,

= enthalpy enu-ring the

h,

=

Y D = displacement rate of compressor D = diameter of cylinder (bore) L = length of stroke N = number of cycles completed per unit time N = (n ) (1) (number of cylinders) for single-acting compressor . N = (n ) (2) (number of cylinders) for double-acting compressor n = compressor speed

expansion valve, kJlkg

enthalpy leaving the expansion valve, kJlkg

Evaporator

/~

1kI~

~hl

7' qe

=h

I

/,Q.

m~

- h4

qe = h I - h3

r--.

7 Qe

= mth, -

A single-acting compressor makes one complete cycle in one rr-voluti on.

h)

Q e = m (h I - h) 3

ll!l('

A double-acting compressor makes two complete cycles in revolution. The actual volumetric efficiency n,"" is defined as n va

qe = refrigerating effect, kJlkg h, = enthalpy entering the evaporator, kJlkg hi = enthalpy leaving the evaporator, kJlkg Qe

=

volume flow rate entering compressor displacement rate of compressor

YI

refrigerating capacity, k,J/s

n VA. =-Y­D

III

.....

h, - h.

The power per kW of refrigeration is the inverse of the coefficient of performance, and an efficient refrigeration system has a low value of power per kW of refrigeration but a high coefficient of performance.

II

I

= -o-h"":;'l_-...."h"':';':l

Ihsplacement rate is the volume swept through by the pistons suction strokes per unit time .

t li.-i r

IIi

Simple Vapor Compression Refrigeration System 17

j{efrir.;l'ration and Air Conditioning

The mechanical efficiency n m is given by

The clearance volumetric efficiency n ve is given by

Pz ] n v e = 1 + c-c [ ~

Uk

[V2 ] = 1 + c-c [V2] ~ = 1-c ~-1

nm

_ WI

_ nIP

- Wn

-

BHP

where JHP = indicated horsepower of the compressor

c = per cent clearance Vc

indicated work brake work

= specific volume of vapor after isentropic

BHP == brake horsepower of the compressor

compression to P, k = 1304 for ammonia ~.

~

"t'

(2-1) A simple saturated refrigeration cycle for R-12 system operates at an evaporating temperature of -5°C and a condensing temperature of 40°C. Determine i a) the refrigerating effect per kg, (b) the work per kg, (c) the heat rejected at the condenser per kg, (d) the COP. For a refrigerating capacity of 1 kW, determine (e) the total heat rejected at the condenser, (f) the work, and (g) the volume flow rate.

SOLUTION

l:I .~

12-14) A 150 x 150-mm, twin-cylinder. -i n u!« ;1('[1111-;

12 compressor running at 25 r l « cu rri o« "

" Irigerating load of 39.4 kW while operating at 340 k Pu - uc t i on

rlld 1277 kPa discharge pressures. If thp discharge [)t"'';-'; 11 1'('

, "fTC' raised to 1397 kPa, at what speed should the co m prr.s sor

I., run to carry the same load assuming the volumetr-ic l,fficIPn('\

r.-m a in the same?

tr i g o r a n t

(d) Effect on eop

For the 40 De condensing cycle,

eop = h 1 - h 4 = 347.1 - 238.5 h 2-h 1 373-347.1

= 419 .

For the 50 0 e condensing cycle,

:IIL( TTl ON

eop = h 1 - h 4 , = 347.1 - 248.9 = 3.18 h 2,-h 1 378-347.1 (e) Effect on work per ton of refrigeration For the 40 0 e condensing cycle, the work,

w .. (m) (h, -

h)= 0.943) (393 - 347.1)

= 50.32 kJ/(min) (ton) or 0.839 kW/ton For the 50 0 e condensing cycle, the work,

.

~

1397kPa

lZr.1kPa

r; _I

t:

"'I

h , = 1\ at 340 kPa =

I

W' = (m') (h, - h.) = (2.149) (378 - 347.1) = 66.40 kJ /Cruin) (ton) or ~.107 kW/ton

~

Enthalpy. kJlq

3~)2,8

k,Jlkg­

h,

=

h

= hi at 1:397 kPa = 2fi:"i.3 kJ/kg

l

h, at 1277 k Pa = 2.'11 k-I/kz

Simple Vapor Compression Refrigeration System :;~l

:18 Rcfriacrat.ion and Air ('()Ilditioning

Let ru

=

old

Ill;\';';

flow rate

For the saturated cycle (cycle 1-2-3-4-1)

m' = nvw m ass flow rate

= old comprt-ssor speed

= now c.nnpresaor speed

n n'

Qp

:30.4 k,J/s

m= h _ h

=

1m')

:39.4 k,J/s :i[)28 - 255.3) k-J/kg

h\- h ,

Iv

l

= h g at --5°C = 349.3 kJ/kg

at --5

DC

= 0.06496 m 3fkg

~J61 k Pa and

S2

equal to

SI

= 3';2 k-I/kg

"or the superheated cycle (cycle 1'-2'-3-4-1')

Q,

= 0.4041

kg/s

4

l

TIl

= 0.071 mVkg

hi' = h at-261 kPa and 15°C = 362 k,Jlkg h 2· = h at 961 kPa and 8 2, equal to 8 1 = 387 k.Jfkg

= ~rYL!2l (n ) Im'lln) n =---

= v at 261 kPa and 15°C

VI'

1m) Iv,)

)

~D2L(2) (n') 4

h,

g

h, = h at

= 0.3870 kg/s

volume flow rate entering compressor . ffici vo I umetnc e Icwncv. = . displacement rate of compressor

J

=V

(:3:")28 - 251) k.I/kg

'I]

111'

v[

=

'II

10.4041) (25)

0.:3870

For the saturated cycle, the refrigerating effect is = h, - h 4 = 349.:3 - 238.5 = 110.8 kJ/kg

Effects of Superheating the Suction Vapor (2-15) A simple saturated r efri gerat ing cycle for R-12 system operates at an evaporating temperature of -boC and a condensing temperature of 40"C. Show the effects of superheating the suction vapor from --5°C to IS-C.

Refrigerating effect

For the superheated cycle, (1) When superheating of suction vapor occurs inside the " frigerated space, useful cooling results and the refr'igeratirg II, -ct is =

SOLUTION

hi' - h 4 = 362 - 238.5 = 123.5 k,Jfkg

(2) When superheating of suction vapor occurs in the ,-Ilon line, no useful cooling results and the refrigerating I',·," is

'I

~.

-

-k----T--7­2'

-; h J

--

h4

= 349.3 -

238.5

= 110.8 kJfII:g

1II'd on mass flow rate per ton 'I'

'11

the saturated cycle, the mass flow rate, =

211 h[ _ h

211 = 349.3 _ 238.5 4

Enthalpy, kJ/kg

h

~

= h, = h, at 40"C = 238.5 kJfkg

= 1.904 kg/train) (ton)

·10 Refrigeration .uid Ail' Conditioning

Simple Vapor Compression Refrigeration

For the su pr-rhc-a t cd cycle,

(11 With useful cooling, the mass flow rate,

211

_

m' = h .- h I

­

..j

1



7.8 kJ/kg

;:: 372.4 kJ/kg

(1.30) (114 kg) (3.35 k.I/kg.C") (29 - 7) Co

;:: 10,992 kJ 10,922 kJ ;:: 29.33 kg/24 h mass of ice;:: 372.4 kJ/kg

(11-4) Four hundred kilograms of poultry enter a chiller at 6°C and are frozen and chilled to a final temperature of -16°C for storage in 12 hours. Compute the product load. specific heat above freezing specific heat below freezing latent heat freezing temperature

3.18 k.I/kg.C" 1.55 k-I/kg.C'' 246 kJ/kg -3°C

SOLUTION

(10 h) (3,600 sth) (3.52 kW/ton) (11-3) A mass of ice at -4°C is needed to cool 114 kg of vegetables in a bunker for 24 hours. The initial temperature of the vegetables is assumed to be 29°C. It is also assumed that the average temperature in the bunker is 7°C, within the 24-hour period. If the heat gained per hour in the bunker is 30% of the heat removed to cool the vegetables from 29°C to 7°C, what would be the required mass of ice? specific heat of ice specific heat of vegetables

1.9387 k-I/kg.C" 3.35 k.I/kg.C"

Q I = (400 kg) (3.18 k-I/kg.C") [6 - (-3)] Q 2 = (400 kg) (246 kJ/kg) Q3 ::: (400 kg) (1.55 k-I/kg.C'') [(-3) - (-16) ] Co

;:: 11,448 kJ ::: 98,400 kJ ::: 8,060 kJ Q::: 117,908 kJ

117,908 kJ ::: 2.73 kW Q::: (12 h) (3,600 s/h)

'fJ'"

"

(

187

186 Refrigeration and Air Conditioning

Table 1 (continued)

Table 2 Refrigeration 11 1"'''1)( -rt ics of liquid and saturated vapor

Enthalpy, kJ/k1

t, DC

P,kPa

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

886.57 915.03 944.18 974.03 1004.6 1035.9 1068.0 1100.7 1134.3 1168.6 1203.7 1239.6 1276.3 1313.9 1352.2 1391.5 1431.5 ·1472.4 1514.3 1557.0 1600.6 1645.1 1690.6 1737.0 1784.3 1832.6 1881.9 1932.2 1983.5 2035.9 W89.2 2143.6 2199.1 2255.6 2313.2

46 47 48 49

SO 51 52 53 54 55

Entropy, kJ/k,· K

Itf

hI

298.527 303.300 308.081 312.870 317.667 322.471 327.284 332.104 336.933 341.169 346.614 351.466 356.326 361.195 366.072 . 370.957 375.851 380.754 385.666 390.587 395.519 400.462 405.416 41fr.382 n5.362 420.358 425.369 430.399 435.450 440.523 445.623 .50.751 455.913 461.112 466.353

1410.41 1411.11 1481.17 1482.53 1483.18 1483.81 1484.42 1485.01 1485.59 1486.14 1486.67 1487.18 1487.66 1488.13 1488.57 1488.99 1489.39 1489.76 1490.10 1490.42 1490.11 1490.98 1491.21 1491.41 1491.58 1491.72 1491.83 1491.88 1491.91 1491.89 1491.83 1491. 73 1491.58 1491.38 1491.12

If

1.34452 1.360S5 1.37654 1.39250 1.40843 1.42433 1.44020 1.45604 1.47185 1.48762 1.50337 1.51908 1.53477 1.55042 1.56605 1.58165 1;59722 1.61276 1.62828 1.64317 1.65924 1.67470 1.69013 1.70554 1.72095 1.73635 1.75174 1.76714 1.78255 1.79798 1.81343 1.82891 1.84445 1.86004 1.87571

"

vf

5.3626 5.3512 5.33'9 5.3286 5.3175 5.3063 5.2953 5.2843 5.2733 5.2624 5.2516 5.2408 5.2300 5.2193 5.2086 5.1980 5.1874 5.1768 5.1663 5.1558 5.1453 5.1349 5.1244 5.1140 5.1036 5.0932 5.0827 5.0723 5.0618 5.0514 5.0409 5.0303 5.0198 5.0092 4.9985

1.6426 1.6466 1.6507 1.6541 1.6588 1.6630 1.66i2 1.6714 1.6757 1.6800 1.6844 1.6888 1.6932 1.6977 1.7023 1.7069 1.7115 1.7162 1.7209 1.7257 1.7305 1.7354 1.7404 1.7454 1.7504 1.7555 1.7607 1.7659 1.7712 1.7766 1.7820 1.7875 1.7931 1.7987 1.8044

v, 144.578 140.214 136.006 131.950 128.037 124.261 120.619 117.103 113.708 110.430 107.263 104.205 101.248 98.3913 95.6290 92.9579 90.3743 87.8748 85.4561 83.1150 80.8484 78.6536 76.5276 74.4678 72.4716 70.5365 68.6602 66.8403 65.0746 63.3608 61.6971 60.0813 58.5114 56.9855 55.5019

t,OC

P, kPa

hf

-30 -25 -20 -15 -10 -8

9.24 12.15 15.78 20.25 25.71 28.20 30.88 33.76 36..86 40.18 41.92 43.73 45.60 47.54 49.53 51.60 53.73 55.93 58.21 60.55 62.97 65.4 7 68.04 70.70 73.43 76.25 79.15 82.14 85.21 H8.38 91.64 94.99

174.25 178.53 182.81 187.09 191.39 193.11 194.83 196.55 198.27 200.00 200.86 201. 73 202.59 203.46 204.32 205:19 206.05 206.92 207.79 208.65 209.52 210.39 211.26 212.13 213.00 213.87 214.74 215.61 216.48 217.35 218.22 219.10 219.97 220.84 221.72 222.59 223.47 224.34 225.22 226.10 227.85 229.61 231.37 233.13 234.90

-6 -4

!

f

~

/­

\

-2 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28' 29 30 32 34 36 38 40

n.44

101.98 105.62 109.37 113.21 117.16 121.22 125.38 134.05 143.18 152.78 162.87 173.46

Specific volume, L/kg

Entropy, kJ/kg· K

Enthalpy. kJ/kg

Specific volume, L/kg

h

x

373\1 37611 37866 381.12 38371 384.80 385.82 386.84 387.86 388.89 389.40 389.91 390.42 390.93 391.44 391.95 392.46 392.97 393.47 393.98 394.49 395.00 395.51 396.02 396.52 397.03 397.54 398.04 398.55 399.05 399.56 400.06 400.57 401.07 401.57 402.07 402.57 403.08 403.58 404.08 405.07 406.07 407.06 408.05 409.04

Sf

0.90099 0.91824 0.93517 0.95179 0.96813 0.97459 0.98100 0.98738 0.9937.1 1.00000 1.00313 1.00625 1.00936 1.01246 1.01555 1.01863 1.02170 1.02476 1.02782 1.03086 1.03389 1.03692 1.03994 1.04294 1.04594 1.04893 1.05191 1.05488 1.05785 1.06080 1.06375 1.06669 1.06961 1.07254 1.07545 1.07838 1.08125 1.08414 1.08702 1.08989 1.09561 1.10130 1.10696 1.11259 1.11819

Sg

1.72074 1.71447 1.70885 1.70377 1.69922 1.69753 1.69592 1.69438 1.69291 1.69150 1.69082 1.69018 1.68951 1.68888 1.68826 1.68766 1.68707 1.68650 1.68594 1.68539 1.68486 1.68434 1.68383 1.68333 1.68285 1.68238 1.68193 1.68148 1.68105 1.68062 1.68021 1.67982 1.67942 1.67905 1.67868 1.67832 1.67798 1.67764 1.67731 1.67699 1.67638 1.67581 1.67527 1.67476 1.67429

vf

vg

0.62466 0.62894 0.63331 0.63777 0.64234 0.64419 0.64606 0.64795 0.64985 0.65178 0.65275 0.65372 0.65470 0.65568 0.65667

1581.77 1225.53 960.954 761.949 610.466 560.196 514.840 473.883 436.764 403.130 387.493 372.593 358.366 344.792 331.859 319.500 307.698 296.427 285.648 275.347 265.483 256.063 247.037 238.396 230.130 222.205 214.614 207.332 200.361 193.665 187.245 181.089 175.166 169.485 164.034 158.786 153.754 148.903 144.246 139.768 131.305 123.462 116.135 109.430 103.151

0.65.7t>6

0.65866 0.65966 0.66067 0.66168 0.66270 0.66327 0.66475 0.66578 0.66682 0.66786 0:66891 0.66997 0.67102 0.67209 0.67316 0.67424 0.67532 0.67641 0.67750 0.67860 0.67971 0.68082 0:68194 0.68307 0.68533 0.68763 0.68995 0.69230 Q.69468

'f'

J 188 Refrigeration and Air Conditioning

189

l

,

Table 2 (continued)

Table 3 Refrigeration 12: properties of liquid and saturated vapor

I

,I

Enthalpy, kJ/tg

1,1

-I

t,OC

P,tPa

hf

hg

If

Ig

vf

45 50 55 60 70 80

202.28 234.64 270.83 311.10 405.15 519.21

239.32 243.75 248.21 252.68 261.68 270.79

411.49 413.93 416.34 418.73 423.42 427.98

1.13206 1.14576 1.15929 1.17267 1.19898

1.67324 1.67237 1.67165 1.67109 1.67031 1.66992

0.70074 0.70700 0.71346 0.72014 0.73421 0.74937

1.2~479

Enthalpy, kJ/kg

Specific volume, L/kg

Entropy. kJ/kg· K

vg

t,OC

~J

~O

89.2884 77.6428 67.8040 59.4543 46.2114 36.3872

,

-55 -50 -45 -40 -35 -30 -28 -26 ..24 -22 -20 -18 -16 -14 -12 -10 -9 -8 -7 ~

-5 -4 -3 -2 -1 0 1 2 3 4 5 6

1 8 9 10 .11 12 13 14 15 16 17 18 19 20

~1 .Ja

"\

P, kPa

22.62 29.98 39.15 50.44 64.17 80.71 100.41 109.27 1.18.72 128.80 139.53 150.93 163.04 175.89 189.50 203.90 219.12 227.04 235.19 243.55 252.14 260.96 270.01 -279.30 288.82 298.59 308.61 318.88 329.40 340.19 351.24 363.55 374.14 386.01 398.15 410.58 423.30 436.31 449.62 463.23 477.14 491.37 505.91 520.76 535.94 551.45 567.29

Entropy, kJ/kg' K

Specific volume, L/kg

f

hg

sf

'«

vf

vg

146.463 150.808 155.169 159.549 163.948 168.369 172.810 174.593 ! 76.380 178.171 179.965 181. 764 183.567 185.374 187.185 189.001 190.822 19"1 :734 192.647 193.562 194.477 195.395 196.313 197.233 198.-154 199.076 200.000 200.925 201.852 202.780 203.710 204 ..6 42 205.575 206.509 207.445 208.383 209.323 210.264 211.207 212.152 213.099 214.048 214.998 215.951 216.906 217.863 218.821

324.236 326.567 328.897 331.223 333.541 335.849 338.143 339.057 339.968 340.876 341.780 342.682 343.580 344.474 345.365 346.252 347.134 347.574 348.012 348.450 348.886 349.321 349.755 350.187 350.619 351.049 351.477 351.905 352.331 352.755 353.179 353.600 354.020· 354.439 354.856 355.272 355.686 356.098 356.509 356.918 357.325 357.730 358.134 358.535 358.935 359.333 359.729

0.77977 0.79990 0.81964 0.83901 0.85805 0.86776 0.89516 0.90244 0.90967 0.91686 0.92400 0.93110 0.93816 0.94518 0.95216 0.95910 0.96601 0.96945 0.97287 0.97629 0.97971 0.98311 0.98650 0.98989 0.99327 0.99664 1.00000 1.00335 1.00670 1.01004 1.01337 1.01670 1.02001 1.02333 1.02663 1.02993 1.03322 1.03650 1.03978 1.04305 1.04632 1.04958 1.05284 1.05609 1.05933 1.06258 1.06581

1.61373 1.60552 1.59810 1.59.142 1.58539 1.57996 1.57507 1.57326 1.57152 1.56985 1.56825 1.56672 1.56526 1.56385 1.56250 1.56121 1.55997 1.55938 1.55897 1.55822 1.55765 1.55710 1.55657 1.55604 1.55552 1.55502 1.55452 1.55404 1.55356 1.55310 1.55264 1.55220 . 1.55176 1.55133 1.55091 1.55050 1.55010 1.54970 1.54931 1.54893 1.54856 1.54819 1.54783 1.54748 1.54713 1.54679 1.54645

0.63689 0.64226 0.64782 0.65355 0.65949 0.66563 0.67200 0.67461 0.67726 0.67996 0.68269 0.68541 0.68829 0.69115 0.69407 0;69703 0.70004 0.70157 0.70310 0.70465 0.70622 0.70780 0.70939 0.71099 0'.71261 0.71425 0-.71590 0.71756 0.71924 0.72094 0.72265 0.72438 0.72612 0.72788 0.72966 0.73146 0.73326 0.73510 (,.73695 0.73882 0.74071 0.74262 0.74455 0.74649 0.74846 0.75045 0.75246

637.911 491.000 383.105 302.683 241.910 195.398 159.375 147.275 136.284 126.282 117.167 108.847 101.242 94.2788 87.8951 82.0344 76.6464 74.1155 71.6864 69.3543 67.1146 64.9629 62.8952 60.9075 58.9963 57.1579 55.3892 53.6869 52.0481 50.4700 48.9499 47.4853 . 46.0737 44.7129 43.4006 42.1349 40.9137 39.7352 38:5975 37.4991 36.4382 35.4133 34.4230 33.4658 32.5405 31.6457 30.7802

h

~ 190 Refrigeration and Air Conditioning

191

Table 3 (continued)

Table 4 Refrigeration 22: properties of liquid and saturated vapor

Enthalpy, kJjkg

Entropy, kJjkg' K

-----t,OC

j,

I'

11\

,J

j

~I:1 Ii ~II

I,

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 52 54 56 58 60 62 64 66 68 70 75 80 85 90 95 100

P,kPa

583.47 599.98 616.84 634.05 651.62 669.54 687.82 706.47 725.50 744.90 764.68 784.85 805.41 826.36 847.72 869.48 891.64 914.23 937.23 960.65 984.51 1008.8 1033.5 1058.7 1084.3 1110.4 1136.9 1163.9 1191.4 1219.3 1276.6 1335.9 1397.2 1460.5 1525.9 1593.5 1663.2 1735.1 1809.3 1885.8 2087.5 2304.6 2538.0 2788.5 3056.9 3344.1 ------

hf

-

219.783 220.746 221.712 222.680 223.650 224.623 225.598 226.576 221.557 228.540 229.526 230.515 23.1.506 232.501 233.498 234.499 235.503 236.510 237.521 238.535 239.552 " 240.574 241.598 242.627 243.659 244.696 245.736 246.781 241.830 248.884 251.004 253.144 255.304 257.486 259;690 261.918 264.172 i66.452 268.762 271.102 277.100 283.341 289.879 296.788 304.181 312.261 ---~.

hg

sf

Sg

360.122 360.514 360.904 361.291 361.676 362.059 362.439 362.817 363.193 363.566 363.937 36'4.305 364.670 365.033 365.392 365.749 366.103 366.454 366.802 367.146 367.487 367.825 368.160 368.491 368.818 369.141 369.461 369.777 370.088 370.396 370.997 371.581 372.145 372.688 373.210 373.707 374.180 374.625 375.042 375.427 376.234 376.777 376.985 376.748 375.887 374.070

1.06904 1.07227 1.07549 1.07871 1.08193 1.08514 1.08835 1.09155 1.09475 1.09195 1.10115 1.10434 1.10753 1.11072 1.11391 1.11710 1.12028 1.12347 1.12665 1.12984 1.13302 1.13620 1.13938 1.14251 1.14575 1.14894 1.15213 1.15532 1.15851 1.16170 1.16810 1.17451 1.18093 1.18738 1.19384 1.20034 1.20686 1.21342 1.22001 1.22665 1.24347 1.26069 1.27845 1.29691 1.31637 1.33732

1.54612 1.54579 1.54547 1.54515 1-.54484 1.54453 1.54423 1.54393 1.54363 1.54334 1.54305 1.54276 1.54247 1.54219 1.54191 1.54163 1.54135 1.54107 1.54079 1.54051 1.54024 1.53996 1.53968 1.53941 1.53913 1.53885 1.5'3856 1.53828 1.53199 1.53770 1.53712 1.536'51 1.53589 1.53524 1.53457 1.53387 1.53313 1.53235 1.53153 1.53066 1.52821 1.52526 1.52164 1.51708 1.51113 1.50296

Specific volume, L/kg vf

Enthalpy, kJ/kg

vg

i.rc

P, kPa

hf

hg

~O

37.48 49.47 64.39 82.71 104.95 131.68 163.48 177.76 192.99 209.22 226.48 244.83 264.29 284.93 306.78 329.89 354.30 367.01 380.06 393.47 407.23 421.35 435.84 450.70 465.94 481.57 497.59 514.01 530.83 548.06 565.71

134.763 139.830 144.,959 150.153 155.414 160.742 166.140 168.318 170.507 172.708 174.919 177.142 179.376 181.622 183.878 186.147 188.426 189.571 190.718 191.868 193.021 194.176 195.335 196.497 197.662 198.828 200.000 201.174 202.351 203.530 204.713 205.899 207.089 208.281 209.477 210.675 211.877 213.083 214.291 215.503 216.719 217.937 219.160 220.386 221.615 222.848 224.084

379.114 381.529 383.921 386.282 388.609 390.896 393.r38 394.021 394.896 395.762 396.619 397.467 398.305 399.133 399.951 400.759 401.555 401.949 402.341 402.729 403.114 403.496 403.876 404.252 404.626 404.994 405.361 405.724 406.084 406.440 406.793 407.143 407.489 407.831 408.169 408.504 408.835 409.162 409.485 409.804 410.119 410.430 410.736 411.038 411.336 411.629 411.9J8

'

-----------_.- .. ----.

-----_.­

0.75449 0.75655 0.75863 0.76073 0.76286 0.76501 0.76716 0.76938 0.77161 0.77386 0.77614 0.77845 0.78079 0.18316 0.78556 0.78799 0.79045 0.79294 0.79546 0.79802 0.80062 0.80325 0.80592 0.80863 0.81137 0.81416 0.81698 0.81985 0.82277 0.82573 0.83119 , 0.83804 0.84451 0.85121 0.85814 0.86534 0.87282 0.88059 0.88870 0.89716 0.92009 0.94612 0.97621 1.01190 1.05581 1.11311

29.9429 29.1327 28.3485 27.5894 26.8542 26.1422 25.4524 24.7840 24.1362 23.5082 22.8993 22.3088 21.735'9 21.1802 20.6408 20.1173 19.6091 19.1156 18.6362 18.1706 17.7182 17.2785 16.8511 16.4356 16.0316 15.6386 15.2563 14.8844 14.5224 14.1 ?01 13.4931 lZ.8509 12.2412 11.6620 11.1113 10.5872 10.0881 9.61234 9.15844 8.72502 7.12258 6.82143 6.00494 5.25759

-55 -50 ~5

f

i "

-40 -35 -30 -28 -26 -24 -22 -20 -18 -16 -14 -12 -10 -9 -8 -7 ~

-5 -4 -3 -2 -1 0 1 2 3 4 5

6

3

4.563~~ 3.90280

\,

~

7 8 9 10 11 12 13 14 15 16 17 18 19 20

5~n.78

602.28 621.22 640.59 660.42 680.70 701.44 722.65 744.33 766.50 789.15 812.29 835.93 860.08 884.75909.93

Entropy, kJ/kg • K sf

0.73254 0.75599 0.77919 0.80216 0.82490 0.84743 0.86976 0.87864 0.88748 0.89630 0.90509 0.91386 0.92459 0.93129 0.93997 0.94862 0.95725 0.96155 0.06585 0.97014 0.97442 0.97870 0.98297 0.98724 0.99150 0.99575 1.00000 1.00424 1.00848 1.01271 1.01694 1.02116 1.02537 1.02958 1.03379 1.03799 1.04218 1.04637 1.05056 1.05474 1.05892 1.06309 1.06726 1.07142 1.07559 1.07974 1.08390

Specific volume, L/kg

's 1.87886 1.86389 1.85000 \.83708 1.82504 1.81380 1.80329 1.79927 1.79535 1.79152 1.78779 1.78415 1.78059 1.77711 1.77371 1.77039 1.76713 1.76553 1.76394 1.76237 1.76082 1.75928 1.75775 1.75624 1.75475 1.75326 1.75279 1.75034 1.74889 1.74746 1.74604 1.74463 1.74324 1.74185 1.74047 1.73911 1.73775 1.73640 1.73506 1.73373 1.73241 1.73109 1.72978 1.72848 1.72719 1.72590 1.72462

vf

vg

0.68208 0.68856 0.69526 0.70219 0.70936 0-.71680 0.72452 0.72769· 0.73092 0.73420 0.73753 0.74091 0.74436 0.74786 0.75143. 0.15506 0.75876 0.76063 0.76253 0.76444 0.76636 0.76831 0.77028 0.77226 0.77427 0.77629 0.77834 0.78041 0.7824Q 0.78460 0.78673 0.78889 0.79107 0.79327 0.79549 0.79775 0.80002 0.80232 0.80465 0.80701 0.80939 0.81180 0.81424 0.81671 0.81922 0.82175 0.82431

537.152 414.827 324.557 256.990 205.745 166.400 135.844 125.563 116.214 107.701 99.9362 92.8432 86.3546 80.4103 74.9572 69.9478 65.3399 63.1746 61.0958 59.0996 57.1820 55.3394 53.5682 51.8653 50.2274 48.6517 47 .13~4. 45.6757 44.2702 42.9166 41.6124 40.3556 39.1441 37.9759 36.8493 35.7624 34.7136 33.7013 32.7239 31.7801 30.8683 29.9874 29.1361 28.3131 27.5173 26.7477 26.0032

", 192

Refrigeration and Air Conditioning

I ~ I:I

Table 4 (continued) Enthalpy, kJjkg t,OC

P, kPa

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

935.64 961.89 988.67 1016.0 1043.9 1072.3 1101.4 1130.9 1161.1 1191.9 1223.2 1255.2 1287.8 1321.0 1354.8 1389.2 1424.3 1460.1 1496.5 1533.5 1571.2 1609.6 1648.7 1688.5 1729.0 1770.2 1812.1 1854.8 1898.2 1942.3 2032.8 2126.5 2223.2 2323.2 2426.6 2533.3 2643.5 2757.3 2874.7 2995.9 3316.1 3662.3 4036.8 4442.5 4883.5

~·8

49 50 52 54 56 58 60 62 64 66 68 70 75 80 85 90 95

Entropy. kJjkg • K

"f

hg

Sf

Sg

Vf

225.324 226.568 227.816 229.068

412.202 412.481 412.755 413.025 413.289 413.548 413.802 414.050 414.293 414.530 414.762 414.987 415.207 415.420 415.627 415.828 416.021 416.208 416.388 416.561 416.726 416.883 417.033 417.174 417.308 417.432 417.548 417.655 417.752 417.838 417.983 418.083 418.137 418.141 418.089 41 '.978 417.802 417.553 417.226 416.809 415.299 412.898 409.101 402.653 38'6.708

1.08805 1.09220 1.09634 1.10048 1.10462 1.10876 1.11290 1.11703 1.12116 1.12530 1.12943 1.13355 1.13768 1.14181 1.14594 1.15007 1.15420 1.15833 1.16246 1.16659 1.17073 1.17486 1.17900 1.18315 1.18730 1.19145 1.19560 1.19977 1.20393 1.20811 1.21648 1.22489 1.23'333 1.24183 1.25038 1.25899 1.26768 1.27647 1.2i535 1.29436 1.31758 1.34223 1.36936 1.40155 1.45222

1.72334 1.72206 1.72080 1.71953 1.71827 1.71701 1.71576 1.71450 i.71325 1.71200 1.71075 1.70950 1.70826 1.70701 1.70576 1.70450 1.70325 1.70199 1.70073 1.69946 1.69819 1.69692 1.69564 1.69435 1.69305 1.69174 1.69043 1.68911 1.68777 1.68643 1.68370 1.68091 1.67805 1.67511 1.67208 1.66895 1.66570 1.66231 1.65876 1.65504 1.64472 1.63239 1.61673 1.59440 1.54712

0.82691 0.82954 0.83221 0.83491 0.83765 0.84043 0.84324 0.84610 0.84899 0.85193 0.85491 0.85793 0.86101 0.86412 0.86729 0.87051 0.87378 0.87710 0.88048 0.88392 0.88741 0.89097 0.89459 0.89828 0.90203 0.90586 0.90976 0.91374 0.91779 0.92193 0.93047 0.93939 0.94872 0.95850 Q.96878 0.97960 0.99104 1.00317 1.01608 1.02987 1.06916 1.11810 1.18328 1.28230 1.52064

~30.324

231.583 232.~47

234.115 235.387 236.664 237.944 239.230 240.520 241.814 243.114 244.418 245.727 247.041 248.361 249.686 251.016 252.352 253.694 255.042 256.396 257.756 259.123 260.497 261.877 263.264 266.062 268.891 271.754 274.654 277.594 280.577 283.607 286.690 289.832 293.038 301.399 310.424 320.505 332.616 351.767

'S){j [w '::lWnrOA :l!J!:l::ldS

Specific volume, Ljkg

o

o o

or.

o o

o o

C"!

~

0 0 ~

0 0

v:

o o o

o o

0 ooog 00000 ~r-:~~....:

"'!

N

o

N-

V

g

25.2829 24.5857 23.9107 23.2572 22.6242 22.0111 21.4169 20.8411 20.2829 19.7417 19.2168 18.7076 18.2135 17.7341 17.2686 16.8168 16.3779 15.9517 15.5375 15.1351 14.7439 14.3636 13.9938 13.6341 13.2841 12.9436 12.6122 12.2895 11.9753 11.6693 11.0806 10.5214 9.98952 9.48319 9.00062 8.54016 8.10023 7.67934 7.27605 6.88899 5.98334 5.14862 4.35815 3.56440

2.55133\

o

g~

j~

'