Steam & Combustion Power Cycles Spreadsheet

John Andrew, P.E.

Course Outline

This 10 PDH Professional Development Hour course includes a series of input data and solved output equations in an Excel format. The student will type numerical parameters and Excel will perform the calculations.

Results calculated in an Excel spreadsheet cell are adjusted to a, “What If” value using, “Goal Seek”.

A link is provided to a completely free: “Steam Table Calculator” download.

Topics include applications of the four major thermal power cycles:

A. Carnot Cycle
B. Rankine Cycle
C. Otto Cycle
D. Brayton Cycle

Subject matter is divided into nine worksheets:
1. Summary
2. Units
3. Entropy
4. Steam Turbines
5. Gasoline Engines
6. Diesel Engines
7. Gas Turbines
8. Air Properties
9. Math Tools

The course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

At the conclusion of this course the student will:

• Have a spread sheet useful for steam and combustion power calculations;
• Adjust heat energy parameters to meet design specifications;
• Document design calculations in a spread sheet format;
• Convert common metric and U.S. units;
• Download a free steam tables calculator;
• Calculate power cycle US to Metric units and vise versa automatically;
• Compute the work done by steam moving a piston in a cylinder;
• Determine theoretical maximum thermal power efficiencies;
• Find steam quality change due to throttling devises;
• Determine the maximum pressure increase across a pump directly coupled to a motor;
• Calculate steam turbine power;
• Learn the overall thermal efficiency of typical of a modern stand-alone steam plant;
• Find steam turbine processes steam extraction quality and heat content;
• Compute the Rankin Cycle steam turbine, with superheat and reheat, thermal efficiency;
• Typical coal-fired steam cycle power plant the operating pressure and temperature;
• Learn what most gasoline powered automobile engine compression ratios are;
• Find the Otto cycle spark-ignition engine thermal efficiency;
• Calculate the Otto cycle spark-ignition engine mean effective pressure;
• Determine the maximum dynamometer brake horse power that an engine can develop;
• Find Otto cycle engine indicated horse power;
• Learn what most diesel powered automobile engine compression ratios are;
• Determine the diesel cycle thermal efficiency;
• Calculate the diesel cycle engine mean effective pressure;
• Learn the overall thermal efficiency of typical gas turbines driving an alternator;
• Determine the back work ratio of a Brayton cycle gas turbine;
• Calculate the thermal efficiency of a Brayton cycle gas turbine;
• Properties of standard air chart included;
• Use Excel to make calculations based on input data; and
• Use Excel to make, “what if calculations” using, "Goal Seek".
  

Intended Audience

The information will be especially useful to: students, engineers, and innovators who need tools for creative steam and combustion power cycle engineering.

Benefit to Attendees

Attendee of this course will be able to calculate and optimize variables in a useful range steam and combustion power cycle engineering projects.

Course Introduction

Excel spread sheets are used in this course to calculate and optimize power cycle parameters. Spread sheets can be stored indefinitely and accessed electronically. Optimizing design values with spreadsheets is very convenient and is often more accurate than hand calculations.

Previously calculations have been done with a calculator and written by hand with pen or pencil. Optimizing design values with a calculator is difficult and time consuming. Quite often it is impossible to read and check these documents. As time passes sometime these documents are lost or are difficult to read.

It becomes difficult to use these hand written often illegible documents to make improvements to existing designs. Spread sheets can be stored indefinitely and accessed electronically.

Course Content

You need to download and study the following spreadsheet:

Steam & Combustion Power Cycles Spreadsheet

DISCLAMER: "This spreadsheet is provided for illustrative teaching purpose only, and is not intended for use in any specific project. Anyone making use of theinformation contained in this spreadsheet does so at his/her own risk and assumes any and all resulting liability arising therefrom."

Spreadsheet Method
Four parameters are input in the example below and all calculations are performed by Excel.

Air Standard Otto Cycle Example	Input
Compression ratio,  r = V1/V2 =	10	-
Low temperature,  t1 =	200	deg C
Low pressure,  P1 =	200	kPa
Work output,  Wout =	1000	kj/kg
	Calculation
Specific heat ratio for air,  k = Cp/Cv =	1.4
Otto cycle efficiency,  η =	1 - (1 / (r^(k - 1)))
=	60.2%
T1 =	t1 + 273
=	473	deg K
1-2 is isentropic,  T2 =	T1*(v1/v2)^(k-1)
=	T1*( r )^(k-1)
=	1188	deg K
Air specific heat constant vol,  Cv =	0.717	kj/kg deg C
Air specific heat constant pressure,  Cp =	1.00	kj/kg deg C
Given cycle net work,  Wout =	1000	kg/kg
and Otto cycle net work,  Wout =	Cv*(T1 - T2) + Cv*(T3 - T4)
T3 - T4 =	(Wout - Cv*(T1 - T2)) / Cv
T3 - T4 =	2110	Equation-1
3-4 is isentropic,  T3 =	T4*(v4/v3)^(k-1)
=	T4*( r )^(k-1)
T3 / T4 =	( r )^(k-1)
T3 / T4 =	2.512	Equation-2
Solving equations 1 and 2 simultaneously:
T3 =	3505	deg K
T4 =	1395	deg K
Carnot cycle efficiency,  ηcarnot =	1 - TLOW / THIGH
=	1 - (T1 / T3)
=	86.5%

Course Summary

This course provides Excel spread sheets to calculate a range of basic power cycle parameters. All variables can be adjusted to optimize design goals. Excel print-outs of design parameters and calculated results provide easy to read documentation for checking and future improvements.

Related Links

Ref. Mechanical Engineering Reference Manual by M Lindburg

Thermodynamics for Engineers by M.C. Potter and C. W. Somerton.

Thermal engineering topics at Wikipedia: http://en.wikipedia.com/wiki/Main_Page

Quiz

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

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DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.

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