For the ideal Rankine cycle case where the feed pump and turbine are isentropic, andthe electric motor on the feed pump and the electric generator are 100% efficient: A.Calculate the specific enthalpy and specific entropy of the refrigerant at the entry andexit of the feed pump, and the entry and exit of the turbine/expander. Also calculatetemperature at the exit of the turbine.We have: Refrigerant: R134ABoiler working pressure: 1200kPa (absolute)Refrigerant temperature after boiling: 68.64 °CAmount of heat available from geothermal water: directly proportional to 5 degreesdrop of geothermal water.Geothermal water specific heat capacity: 4.2 kJ/kg.KBoiler to turbine isentropic efficiency: 81.6%Boiler feed pump isentropic efficiency: 87.3%Condenser saturation pressure: 723kPaElectric Generator Efficiency: 83.33Efficiency of electric motor driving boiler pump: 81.6%

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Answered: For the ideal Rankine cycle case where…

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

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For the ideal Rankine cycle case where the feed pump and turbine are isentropic, and
the electric motor on the feed pump and the electric generator are 100% efficient: A.
Calculate the specific enthalpy and specific entropy of the refrigerant at the entry and
exit of the feed pump, and the entry and exit of the turbine/expander. Also calculate
temperature at the exit of the turbine.
We have: Refrigerant: R134A
Boiler working pressure: 1200kPa (absolute)
Refrigerant temperature after boiling: 68.64 °C
Amount of heat available from geothermal water: directly proportional to 5 degrees
drop of geothermal water.
Geothermal water specific heat capacity: 4.2 kJ/kg.K
Boiler to turbine isentropic efficiency: 81.6%
Boiler feed pump isentropic efficiency: 87.3%
Condenser saturation pressure: 723kPa
Electric Generator Efficiency: 83.33
Efficiency of electric motor driving boiler pump: 81.6%

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Follow-up Question

Using that information and this table

For the average monthly rate of geothermal heat available, determine, for the real case: in a tabular format and show sample calculation for one month.

the necessary monthly average mass flow rate (in kg/s) of the refrigerant that must be pumped through the heat exchanger to collect the thermal energy from the available geothermal hot water flow rate if the hot water was cooled by 5°C. What should be the flow capacity (in kg/s) of feed pump of the ORC heat engine that you are designing and the monthly average net electric power generation capacity (in kW).

2. the monthly average net electric power generation capacity (in kW) and yearly average net electrical power generation capacity (in kW).

Month
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Geothermal
resource
Monthly average
hot water flow rate
kg/sec
29.95
31.44515578
31.93608763
31.09306033
29.48229461
28.18566401
28.07405269
29.22242459
30.85947375
31.88567332
31.61177459
30.22174213
Monthly average
temperature
°C
73.64
73.64
73.64
73.64
73.64
73.64
73.64
73.64
73.64
73.64
73.64
73.64
Electrical load
Irrigation pumps
kW
5.479690788
5.961199319
6.256651279
5.237915066
3.589226597
2.417930298
2.510729328
3.80529506
5.43213021
4.639600431
6.298568171
5.479690788
Packaging facility
kW
37.48944285
37.29775673
36.59402913
35.96147705
35.82495517
36.27615864
37.01203589
37.5383337
37.50156325
35.83852601
36.92642148
37.48944285
Cold Storage
kW
10.3429181
9.859688382
9.470699203
9.437215808
9.781727377
10.27284213
10.58070199
10.49853238
10.08152264
9.609758079
9.400100173
9.786059837

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I want a step by step working out on how all these values were obtained and what table was used

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Follow-up Question

Considering now the real case, where the turbine and feed pump are not isentropic, and the feed pump electric motor and the electric generator are not 100% efficient:

Calculate the actual specific enthalpy and actual specific entropy and the actual temperature of the refrigerant at the exit of the feed pump, and the exit of the turbine/expander;

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Follow-up Question

What if the turbine and feed pump are not isentropic what would be the actual specific enthalpy and actual specific entropy and the actual temperature of the refrigerant at the exit of the feed pump, and the exit of the turbine/expander.

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Follow-up Question

could u give me a brief explanation on how to read the table of r134A as well?

Using the above information and this table (if needed)
Monthly average Monthly average
hot water flow rate temperature
kg/sec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
29.95
31.44515578
31.93608763
31.09306033
29.48229461
28.18566401
28.07405269
29.22242459
30.85947375
31.88567332
31.61177459
30.22174213
°C
73.64
73.64
73.64
73.64
73.64
73.64
73.64
73.64
73.64
73.64
73.64
73.64
Irrigation pumps
kw
5.479690788
5.961199319
6.256651279
5.237915066
3.589226597
2.417930298
2.510729328
3.80529506
5.43213021
4.639600431
6.298568171
5.479690788
Determine for unit mass flow rate (i.e. 1kg/s) of refrigerant circulated:
Packaging facility
kW
A. Determine for unit mass flow rate (i.e. 1kg/s) of refrigerant circulated:
37.48944285
37.29775673
36.59402913
35.96147705
35.82495517
36.27615864
37.01203589
37.5383337
37.50156325
35.83852601
36.92642148
37.48944285
Cold Storage
kw
10.3429181
9.859688382
9.470699203
9.437215808
9.781727377
10.27284213
10.58070199
10.49853238
10.08152264
9.609758079
9.400100173
9.786059837
I.
the necessary electrical power input for the boiler feed pump motor (in kW);
II. the electric power output of the generator (in kW);
III. the net electric output power (in kW);
IV. the rate of heat delivery to the fluid in the boiler (in kW);
V. the rate of heat rejection at the condenser (in kW);
VI. The efficiency of conversion of the heat energy put into the fluid, to net electrical energy
(in %).

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