Engineering, 14.02.2020 23:10 Riddledjam44623

The air conditioner in an automobile uses R-134a as the refrigerant. The compressor power input is 1.5 kW which brings the R-134a from 200 kPa to 1200 kPa by compression. The cold-space heat exchanger cools atmospheric air from an outside temperature of 30°C down to 10°C and blows it into the car. What is the mass flow rate of the R‐134a and what is the low-temperature heat transfer rate? What is the mass flow rate of air to achieve a temperature of 10°C? Assume air is an ideal gas and there is 100% heat transfer in the evaporator.

Answers: 2

Show answers

Answers

Answer from: xonyemaa12

Mass flow rate of R-134a is m = 0.0403 kg/s

Hence, the low-temperature heat transfer rate (Q) = 5.087 kW

The mass flow rate of air to achieve a temperature of 10°C = 0.253 kg/sec

Explanation:

Given that:

The compressor power input is 1.5 kW,

Which brings the R-134a from 200 kPa to 1200 kPa by compression.

i.e The compressor inlet pressure P₁ = 200 kPa and the compressor outlet pressure P₂ = 1200 kPa

The cold-space heat exchanger cools atmospheric air from an outside temperature of 30°C down to 10°C and blows it into the car.

This is telling us more information about the Maximum Temperature and Minimum Temperature.

Maximum Temperature = 30 °C

Minimum Temperature = 10 °C

Change in temperature (ΔT) = 20 °C

At P₁ = 200 kPa from saturated P-134a tables.

h₁ = hg = 392.28 kJ/kg

s₁ =sg = 1.7319 kJ/kg. K

At P₂ = 1200 kPa from super-heated tables

s₂ = sg = 1.7319 kJ/kg.K

h₂ = 429.526 kJ/kg

To determine the mass flow rate of the R-134a,we need to first find the Specific compressor work which is given by the formula:

w = h₁ - h₂

where h₁ = 392.28 kJ/kg

h₂ = 429.526 kJ/kg

w = (392.28 - 429.526) kJ/kg

w = -37.246 kJ/kg

W = mw

-1.5 = m × (-37.246)

m = 0.0403 kg/s

Mass flow rate of R-134a is m = 0.0403 kg/s

If P₂ = 1200kPa, then hf= h₃= h₄= 266.055 kj/kg

Therefore; the low-temperature heat transfer rate(Q) can be calculated by the formula;

Q= m(h₁ - h₄)

Q= 0.0403 ( 392.28 - 266.055)

Q= 5.087 kW

Hence, the low-temperature heat transfer rate (Q) = 5.087 kW

What is the mass flow rate of air to achieve a temperature of 10°C?

$Q= m_{air}C_p(T_2-T_1)$

5.087 = $m_{air}$ (1.004)(20)

$m_{air}$ = $\frac{5.087}{1.004*20}$

$m_{air}$ = 0.253 kg/sec

∴ The mass flow rate of air to achieve a temperature of 10°C = 0.253 kg/sec

The air conditioner in an automobile uses R-134a as the refrigerant. The compressor power input is 1

Answer from: Quest

1.jews

2.poles

3.russians

4.gypsies

5. african americans

< 3

Answer from: Quest

angvrswer:

vfg

grfhrtrhr:

jjj

yjujuju

jujuhuyhyt

bgf

bgr

gbr

bgr

gtr

bgr

gbgbbg

bgg

bbg

bfg

dcwf

fdb

ggb

rfe

gtg

gegte

gff

dfg

gfdsax

cvfbgnh

jmhngf

dsaazxscvb

nmhgb

fvdcsxaz

zxcv

bghn

Another question on Engineering

Engineering, 03.07.2019 14:10

If the thermal strain developed in polyimide film during deposition is given as 0.0044. assume room temperature is kept at 17.3 c, and thermal coefficient of expansion for the film and the substrate are 54 x 10^-6c^-1 and 3.3 x 10^-6c^-1respectively. calculate the deposition temperature.

Answers: 3

Answer

Engineering, 04.07.2019 18:10

Ajournal bearing has a journal diameter of 3.250 in with a unilateral tolerance of 20.003 in. the bushing bore has a diameter of 3.256 in and a unilateral tolerance of 0.004 in. the bushing is 2.8 in long and supports a 700-lbf load. the journal speed is 900 rev/min. find the minimum oil film thickness and the maximum film pressure for both sae 20 and sae 20w-30 lubricants, for the tightest assembly if the operating film temperature is 160°f. a computer code is appropriate for solving this problem.

Answers: 3

Answer

Engineering, 04.07.2019 18:10

True or false (explain) (110)[111] is a slip system in bcc metals . the {111} family in fcc contains 8 planes. resolved shear stress (rss) in single crystals is just related to the applied stress. critical resolved shear stress (crss) in single crystal metals is direct proportional to the number of defects in the structure

Answers: 2

Answer

Engineering, 04.07.2019 18:20

Have a greater impact on maintenance productivity than any other support group. (clo5) a)-the top management b)-inventory and purchasing c)-sub-contracting d)-cmms

Answers: 2

Answer

You know the right answer?

The air conditioner in an automobile uses R-134a as the refrigerant. The compressor power input is 1...

Questions