Bryan Tibbetts California State University, Sacramento Fall 2012.

Stirling Cycle and Engines

Bryan TibbettsCalifornia State University, Sacramento

Fall 2012

Reverend Dr. Robert StirlingBorn: October 25, 1790Died: June 6, 1878Studied divinity at the University of Glasgow and the University of Edinburgh.Became a minister of the Church of Scotland.Obtained a patent for his “Heat Economiser” in 1816.“Heat Economiser” now called the regenerator.Built first practical engine in 1818 used to pump water out of a quarry.

The thermodynamic cycle driving Stirling’s engine was not completely understood until the work of Sadi Carnot (1796 - 1832) and was named the Stirling Cycle.

Ideal Stirling Cycle

2 3: Isothermal expansion

3 4: Isometric heat rejection

4 1: Isothermal compression

1 2: Isometric heat addition

Stirling Cycle P-V Diagram

P

V

2

3

4

1

Qin

Qout

Cycle is reversible, and so can be mechanically powered to operate as a heat pump for cooling.

T = const

T = const

QR

QR

Ideal Stirling CycleStirling Cycle P-V Diagram

P

V

2

3

4

1

Qin

Qout

T = const

T = const

QR

QR

Regenerator

Stirling Cycle P-V Diagram

P

V

2

3

4

1

Qin

Qout

T = const

T = const

QR

QR

Thermodynamic Optimization of a Stirling Engine

Model based on Ford-Philips 4-215 engine

Authors: M.C. Campos, J.V.C. Vargas, J.C. Ordonez


Dimensionless Equations Describing System


Solved numerically using an adaptive time step fourth-fifth order Runge-Kutta method


Optimized Efficiency and Work Plot


Two-way maximized system efficiency (ηmax,max) based on optimization of two system characteristic parameters, φ and y.

φ is the ratio of the swept expansion volume over the total swept volume.

y is the ratio of the hot side heat transfer area over the total heat transfer area.

Finite Time Thermodynamic Evaluation of Endoreversible Stirling Heat Engine at Maximum

Power Conditions

Finite Time Thermodynamic analysis accounts for a finite temperature difference between the hot and cold sources and the working fluid of the engine (required for heat transfer to occur) and the finite amount of heat transferred in a finite time period per process.

Author: Iskander Tlili


Power Conditions

Regenerator effectiveness only effects Thermal Efficiency

Hot and cold side heat exchanger effectiveness only effects maximum power output



Power Conditions

Temperatures of the external hot and cold source fluids effect both the thermal efficiency and maximum power output


Thermodynamic Study on Optimal Solar Stirling Engine Cycle Taking Into Account the Irreversibilities

EffectsAuthor: Iskander Tlili

Model based on General Motors GPU-3 engine



Equations Describing System



Results

Oscillating Flow in a Stirling Engine Heat Exchanger

No correlations existed for calculating heat transfer coefficient and friction factor in oscillating flow

Annular Effect occurs in oscillating flow in a pipe, which is the maximum flow velocity occurs near the wall instead of the center of the pipe

Fluid flow in a Stirling engine is comprised of laminar, transitional, and turbulent flows during every cycle

Pressure losses for various geometries were also analyzed:

Authors: M. Kuosa, K. Saari, A. Kankkunen, T.-M. Tveit

Problem Approached

Oscillating Flow in a Stirling Engine Heat ExchangerAuthors: M. Kuosa, K. Saari, A. Kankkunen, T.-M. Tveit

Equations


Nu vs. Re plot


Results

The pressure losses and Nusselt numbers were examined

to determine that designs which form thinner boundary

layers along the length of heat exchanger tubes but do not

significantly increase the dead volume space or pressure

losses are recommended

Analytical Model for Predicting the Effect of Operating Speed on Shaft Power Output of Stirling Engines

Authors: Chin-Hsiang Cheng, Hang-Suin Yang

Questions?

References:1. M.C. Campos, J.V.C. Vargas, J.C. Ordonez, Thermodynamic optimization of a Stirling engine, Energy, Volume

44, Issue 1, August 2012, Pages 902-910, ISSN 0360-5442, 10.1016/j.energy.2012.04.060.2. Iskander Tlili, Finite time thermodynamic evaluation of endoreversible Stirling heat engine at maximum power

conditions, Renewable and Sustainable Energy Reviews, Volume 16, Issue 4, May 2012, Pages 2234-2241, ISSN 1364-0321, 10.1016/j.rser.2012.01.022.

3. Iskander Tlili, Thermodynamic Study on Optimal Solar Stirling Engine Cycle Taking Into Account the Irreversibilities Effects, Energy Procedia, Volume 14, 2012, Pages 584-591, ISSN 1876-6102, 10.1016/j.egypro.2011.12.979.

4. M. Kuosa, K. Saari, A. Kankkunen, T.-M. Tveit, Oscillating flow in a stirling engine heat exchanger, Applied Thermal Engineering, Volumes 45–46, December 2012, Pages 15-23, ISSN 1359-4311, 10.1016/j.applthermaleng.2012.03.023.

5. Chin-Hsiang Cheng, Hang-Suin Yang, Analytical model for predicting the effect of operating speed on shaft power output of Stirling engines, Energy, Volume 36, Issue 10, October 2011, Pages 5899-5908, ISSN 0360-5442, 10.1016/j.energy.2011.08.033.

Bryan Tibbetts California State University, Sacramento Fall 2012.

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