Fluid Lab Report

In: Science

Fluid Lab Report

Experimental Observations

This section of the report contains results from experimental observation of the R713 Hilton   refrigeration unit during its operation. The experimental result are required for calculations relevant for the analysis of the first law within the unit;

Ambient Temperature: 22.2 (C

Ambient Pressure : 754.9 mm Hg

Compressor Speed: 472 rev/min

Load on Dynamometer arm 9.25 N

Evaporator Current: 4.5 A

Evaporator Voltage: 200 V

Condenser Flow Rate: 483 g/s

Condenser Temp (inlet) 13.7 (C

Condenser Temp (exit) 20.8 (C

Condenser Pressure: 590 kPa (gauge)

Evaporator Pressure: 190 kPA (gauge)

Compressor Temp (inlet) 9.6 (C

Compressor Temp (exit) 43 (C

Condenser Temp (exit) 23.7 (C

Evaporator Temp (inlet) 0.4 (C

Calculations

Mass flow rate of R134a around Evaporator

Q L = (V)(A)
= (200)(5.4)
= 1080 kW

P3 = 590 kPa           h3 = h4 = 265 kJ/ kg (from table)
T3 = 23.7 (C

P1 = 190 kPa   h1 = 261 kJ/ kg (from table)
T1 = 9.6 (C

Q L   = m (h1 – h4)

m = 1.080 / (261 – 265)
    = 0.270 kg/s

Mass flow rate of R134a around Condenser

QH = mcw * Cp (water) (Tcw, in – Tcw, out)
      = (0.483)(4.18)(13.7 – 20.8)
    = 14.33 kJ/s

P2 = 590 kPa     h2 = 283 kJ/ kg   (from table)
T2 = 43 (C

P3 = 590 kPa             h3 = h4 = 265 kJ/ kg (from table)
T3 = 23.7 (C

QH   = m (h2 – h3)

m = 14.3 / (283 – 265)
    = 0.8 kg/s

Power input to the Compressor

Ps (shaft power) = F * (0.053218) *   nc
                          = (9.25)(0.053218)(7.87)
                          = 3.82 kW

Power Factor = Pa / Ps
Pa = (0.57)(3.87)
    = 2.207 kW

Calculations Continued

Coefficient of Performance for the Refrigerator

( = QL / Wc

Wc = Pa

( = 1.080 / 2.207
  = 0.49

Rate of Heat Transfer from the Compressor

Win = Qout + m (he – hi)

me = mi = m   therefore   m = 0.207 kg/s

Win = 2.207 kW

P1 = 190 kPa     h1 = 261 kJ/ kg   (from...

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