An analysis of beta type Stirling engine with rhombic drive mechanism D.J. Shendage a , S.B. Kedare a , S.L. Bapat b, * a Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India b Department of Mechanical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India article info Article history: Received 27 October 2009 Accepted 28 June 2010 Available online 24 July 2010 Keywords: Stirling engine Rhombic drive Overlapping volume abstract Stirling engine system is one of the options for electrifying a remote community not serviceable by the grid, which can operate on energy input in the form of heat. Major hurdle for the wide-spread usage of rhombic drive beta type Stirling engine is complexity of the drive and requirement of tight tolerances for its proper functioning. However, if the operating and geometrical constraints of the system are accounted for, different feasible design options can be identified. In the present work, various aspects that need to be considered at different decision making stages of the design and development of a Stirling engine are addressed. The proposed design methodology can generate and evaluate a range of possible design alternatives which can speed up the decision making process and also provide a clear understanding of the system design considerations. The present work is mainly about the design methodology for beta type Stirling engine and the optimization of phase angle, considering the effect of overlapping volume between compression and expansion spaces. It is also noticed that variation of compression space volume with phase angle remains sinusoidal for any phase difference. The aim of the present work is to find a feasible solution which should lead to a design of a single cylinder, beta type Stirling engine of 1.5 kW e capacity for rural electrification. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Stirling engines are again becoming relevant due to shortage and high cost of fossil fuel. Stirling engines can run quietly on combus- tion of any fuel. These do not use valves and are generally compact and reliable, as combustion takes place outside the working space. Stirling engines also do not have the Ozone depletion potential. Stirling engines work on Stirling cycle and have high efficiency. The ideal Stirling cycle consists of two isothermal and two isochoric processes as depicted on PeV diagram in Fig. 1 . The cycle operates between minimum and maximum temperatures, T C and T E . The limit on T E is dependent on the material of construction for the system. The regenerator is a thermodynamic sponge, a porous mass of finely divided material and alternately accepts (process 4e1) and rejects (process 2e3) heat from working fluid as shown in Fig. 1 . Since Stirling engines are external heat source engines, they can also operate on concentrated solar energy and any gaseous or liquid fuels. Thermal efficiency of Stirling engine is expected to be higher than that of Rankine cycle based systems. Stirling engine may also prove to be cheaper compared to solar photovoltaic units for 1.5 kW e capacity. There are 96,000 villages in India to be electrified [1]. Of these more than 20,000 villages are in remote and difficult areas of the country, 3e30 km away from grid, with number of households below 200, average population less than 500, with time for power requirement quite low (of the order of 4e6 h/day) for minimal facilities. The grid connection for such villages is a very costly proposition and hence not easily taken up. Therefore, a Stirling engine with capacity of about 1.5 kWe seems to be the most viable option. It will, at least partially, help to overcome the present problem of scarcity of electrical energy in India, especially in remote regions. If biomass or agricultural waste is available as fuel many more applications may come up at small companies and communities [2]. Stirling engines of various configurations are developed over the years. Also different analysis methodologies are used for the purpose of analysis and comparison between systems. Shoureshi has compared Stirling, Rankine and Brayton engines at different practical temperature-ratios conditions and shows that Stirling engines are more efficient than others [3]. The “V”-type Stirling engines with sealed and dry crank-cases and fuelled by natural gas are presently under development at the Physical-Technical Institute and one of the major issues in improving kinematic Stirling engine performance was proper guiding of piston rings, while developing Radioisotope Stirling engines [4]. In other words, one has to design drive mechanism such that it should have minimum side thrust and * Corresponding author. Fax: þ91 22 25 72 68 75. E-mail addresses: shendagedj@iitb.ac.in (D.J. Shendage), sbkedare@iitb.ac.in (S.B. Kedare), slbapat@iitb.ac.in (S.L. Bapat). Contents lists available at ScienceDirect Renewable Energy journal homepage: www.elsevier.com/locate/renene 0960-1481/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.renene.2010.06.041 Renewable Energy 36 (2011) 289e297