Thermodynamics lab: Heat Engine Examination

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Homework Help Overview

The discussion revolves around a thermodynamics lab problem related to a heat engine, specifically focusing on calculating power, efficiency, and the air to fuel ratio based on provided parameters such as torque, speed, temperatures, and fuel properties.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate the mass flow rate of the fuel but is uncertain about the necessary formulas and the meaning of certain parameters, particularly the speed measurement.

Discussion Status

Participants are clarifying the meaning of the speed measurement and its units, with some suggesting it may refer to revolutions per minute rather than volumetric flow. The original poster indicates that the teacher provided clarification, enhancing their understanding of the problem.

Contextual Notes

There is a lack of explicit formulas provided for the calculations, and the original poster expresses confusion regarding the parameters and their interpretations based on the data sheet from the experiment.

CptJackWest
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Homework Statement


Calculate the Power, Efficiency, air to fuel ratio.

torque-3.809Nm
speed-3137.207 l/min
T1 Temperature Exhaust=412.598degC
T2 Temperature Ambient=19.141degC
T3 Temperature Fuel=18.994degC
dv/dt Volumetric Flow Air=109.954 l/min
p fuel Fuel Pressure= 21.475 mbar
calorific value of fuel= 435kj/kg

The only thing I am not sure on is how to calculate the mass flow rate of the fuel.
no formula is given, but tried Q=m(T2-T1) but I don't know Q. any help or tips would be great.
Cheers
Jack
 
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You have speed as 3137.207 l/min. Speed of what? Are these units correct?
 
Thanks for helping.
This problem is from an experiment we did involving an engine.The speed was to stated but I am taking it as the speed of the shaft in the engine. That units that i wrote is what is the data sheet I was given. I did not like the look of them either, but I am now assuming that it in meters per minute.
 
If you measured the speed of an operating engine with a tachometer, then 3137 is more likely measured in revolutions per minute (RPM).
 
Thanks for the help, my teacher ended up explaining the whole thing to me and it is now a lot clearer. The speed was not the speed but the mass flow rate in litres per min.
Thanks a lot for trying to help.
cheers
 

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