ENSC 461
Assignment #8 (Vapor Power Cycles)
Assignment date:
Due date:
Consider a reheat-regenerative vapor power cycle with two feedwater heaters,
a closed FWH and an open FWH. Steam enters the first turbine at 8.0 MPa,
480C and expands to 0.7 MPa. The s

ENSC 461
Assignment #2 (Cycles)
Assignment date: Tuesday Jan 23, 2011
Problem 1: (the Stirling cycle)
Show that for an idealized Stirling cycle, the thermal efficiency is:
th 1
TL
TH
Problem 2: (Otto cycle)
An open, ideal Otto-cycle engine has a compres

PowerCycles
Most power producing devices operate on cycles. To make simple thermodynamics
analysis possible, we use the concept of ideal cycle. These idealized cycles serve as
starting point for more in-depth studies.
Heat engines are designed to convert

ChemicalReactions
When analyzing reacting systems, we need to consider the chemical internal energy,
which is the energy associated with the destruction and formation of chemical bonds
between the atoms. Thermodynamic analysis of reactive mixtures is prim

OpenGasTurbineCycle
Fuel
Combustion
chamber
Turbine
Shaft
Wnet
Compressor
Combustion
products
Air
Fig.1: Schematic for an open gas-turbine cycle.
WorkingPrincipal
Fresh air enters the compressor at ambient temperature where its pressure and
temperature ar

MECH 461
Assignment #3 (Refrigeration)
Assignment date: Tuesday Jan 29, 2011
Problem 1:
Figure below shows a steam jet refrigeration system that produces chilled
water in a flash chamber. The chamber is maintained at a vacuum pressure by
the steam ejector

Exergy
Exergy is the theoretical limit for the work potential that can be obtained from a source or
a system at a given state when interacting with a reference (environment) at a constant
condition.
A system is said to be in the dead state when it is in t

ENSC 461
Assignment #5 (Exergy)
Assignment date:
Due date:
Problem 1:
A system undergoes a refrigeration cycle while receiving Qc by heat transfer
at temperature Tc and discharging energy QH by heat transfer at a higher
temperature TH. There are no other

ENSC 461
Assignment #7 (Non-Reacting Mixtures and HVAC)
Assignment date:
Due date:
Problem 1:
A system consists, initially of nA moles of gas A at pressure P and temperature
T and nB moles of gas B separate from gas A but at the same pressure and
temperat

ENSC 461
Assignment #4 (Gas-turbine)
Assignment date: Tuesday Feb. 08, 2011
Due date: Tuesday Feb. 15, 2011
Problem 1:
An ideal gas-turbine cycle with ideal regeneration and with n-stage of
compression (with intercooling) and expansion (with reheating), e

ENSC 461 Tutorial, Week#2 Ideal Gas
Consider a rigid, insulated tank with a movable piston. Initially side A
contains 25kg of air at 250C and 500kPa, while side B contains 5kg of
air at 70C and 50kPa. The piston then moves to a new position where
the pres

ENSC 461 Tutorial, Week#6 Exergy: Control Mass Analysis
An insulated piston-cylinder device contains 2L of saturated liquid water
at a pressure of 150 kPa which is constant throughout the process. An
electric resistance heater inside the cylinder is turne

ENSC 461 Tutorial, Week#3
Application of the Second Law to an Open System
Two alternative systems are under consideration for bringing a stream of
air from 17C to 52C at an essentially constant pressure of 100 kPa.
System 1: The air temperature is increas

ENSC 461 Tutorial, Week#6
Brayton Cycle with Intercooling, Reheat & Regeneration
A regenerative gas turbine with intercooling and reheat operates at
steady state. Air enters the compressor at 100 kPa, 300 K with a mass
flow rate of 5.807 kg/s. The pressur

ENSC 461 Tutorial, Week#8
Gas Refrigeration Cycles
A refrigeration system using air as the working fluid, consists of an ideal
Brayton cycle run in reverse with a temperature and pressure at the inlet
of the compressor of 37C and 100 kPa. The compressor h

ENSC 461 Tutorial, Week#4 IC Engines
The compression ratio in an air-standard Otto cycle is 10. At the
beginning of the compression stroke the pressure is 0.1 MPa and the
temperature is 15C. The heat transfer to the air per cycle is 1800 kJ/kg.
Determine:

ENSC 461
Assignment #1 (Review)
Problem 1: (the 1st law)
A tank with a volume of 1 m3 is initially evacuated. Atmospheric air at 101.3
kPa leaks into the tank through a weld imperfection. The process is slow and
heat transfer with the surroundings keeps t

ENSC 461 Tutorial, Week#10 - Rankine Cycle
Consider a coal-fired steam power plant that produces 300MW of electric
power. The power plant operates on a simple ideal Rankine cycle with
turbine inlet conditions of 5 MPa and 450C and a condenser pressure of

ENSC 461 Tutorial, Week#9
Non-Reacting Mixtures Psychrometrics Applied to a Cooling Tower
Water exiting the condenser of a power plant at 45C enters a cooling
tower with a mass flow rate of 15000 kg/s. A stream of cooled water is
returned to the condenser

ENSC 461 Tutorial, Week#6 Refrigeration Cycle
A large refrigeration plant is to be maintained at -15C, and it requires
refrigeration at a rate of 100kW. The condenser of the plant is to be
cooled by liquid water, which experiences a temperature rise of 8C