ASEN3113HW5solutionsPART1

8/12/2019 ASEN3113HW5solutionsPART1

1/7

ASEN 3113 Thermodynamics and Heat Transfer

Homework #5

Assigned: October 12, 2006Due: October 18, 2006 (noon)

(Total points noted in each section; must clearly show equations with values and units,

drawings, assumptions, etc.)

1. (20 oints! 15 oints for e"ations! 5 oints for correct answer$

A cold storage room is being used to store strawberries at 1C !"e e#a$orator and condensertem$eratures are %2 and &'C, res$ecti#el !"e rerigeration load is 1' tons (1 ton o

rerigeration load * +'1 -.) Assume t"e rerigerant is /%1+&a Determine t"e ollowing:

(a) !"e rerigerant low rate

(b) !"e com$ressor $ower reuirement(c) CO

(d) !"e "eat reected in t"e condenser

So%tion&3irst determine t"e ent"al$ies in t"e rerigerator Assume t"e luid entering t"e com$ressor is

%2C and a saturated #a$or"1* 2&606 -45-g s1 * 07201 -45-g9

Assume t"e tem$erature eiting t"e condenser is &'C ;oo- u$ t"e #alues or $oint + atsaturated liuid $ro$erties

"+* 11+' -45-g + * 1160


2/7


3/7

2. (20 oints! 15 oints for e"ations! 5 oints for correct answer$

3or a rerigeration sstem using / %1+&a, t"e e#a$orator tem$erature is %'C, "owe#er t"ererigerant entering t"e com$ressor is at 'C !"e condenser tem$erature is +'C, but t"e

rerigerant entering t"e e$ansion #al#e is at +0C

(a) ."at is t"e amount o su$er"eating and subcoolingB(b) t"e rerigeration load is + tons, calculate t"e CO or t"is sstem

olution:(a) u$er"eating is t"e dierence in tem$erature o luid entering com$ressor and e#a$orator

u$ercooling is t"e dierence in tem$erature o luid entering condenser and entering e$ansion

#al#e

( )

( ) !!!TTng&upercooli

!!!TTng&uperheati

valveansionenteringcondenser

evaporatorcompressorentering

'+0+'

10''

Ee:$E

E

==

==

(b) 3irst assume t"at t"e tem$erature o t"e luid entering t"e com$ressor is a saturated #a$or at

'C

;oo- u$ ent"al$ and entro$ at $oint 1 (entering com$ressor)

"1*2'01 -45-g s1 * 0716& -45-g9

Assume isentro$ic e$ansion in com$ressor, s1 * s2 and assume $ressure is constant t"roug" t"e

condenser Assume t"at at t"e eit o t"e condenser, t"e luid is a saturated liuid at +'C ;oo-u$ ent"al$ and saturation $ressure at $oint +

"+ * 788 -45-g aturation ressure F + * 088ecause t"esaturation tem$eratures o 080


4/7

ow linear inter$olate between 080


5/7


6/7

( ) ( )

( )( )sm(

'''kgkJ(

TT!p((

TT!p((

hhwq

'Tk#a

k#a'

#

#TT

5101'61,11+1500+12

222

61,&0+

'2&811+1

6

6

6'6

2

6'6

2

'

2

6'6'6'6

6

&011&0101

'

6'6

==

=+

+=

=

=

=

ro$ulsi#e eicienc (c) answer

( )( )

( )( )

J&16

'8+1&&0500+1

58'058'05101'

+&

116

=

=

==

p

in

p

p'''kgkJ

smsmsm

TT!p

(((

q

w

' (20 oints! 15 oints for e"ations! 5 oints for correct answers$

Consider a steam $ower $lant o$erating as an ideal ran-ine ccle !"e condenser $ressure is

8-a !"e turbine can o$erate at two $ressures, 18


7/7

Documents

ASEN3113HW5solutionsPART1