Stirling engine based solar-thermal power plant with a thermo-chemical storage system Shantanu Acharya ⇑ , Subhadeep Bhattacharjee Department of Electrical Engineering, National Institute of Technology (NIT), Agartala, Tripura 799046, India article info Article history: Received 7 March 2014 Accepted 11 June 2014 Available online 5 July 2014 Keywords: Thermal energy storage Stirling engine Fresnel lens capsule Solar-thermal power generation abstract This paper describes a solar-thermal run Stirling engine based uninterrupted power generating system employing magnesium sulphate impregnated Zeolite pellets for thermal energy storage. In the proposed system, Stirling engine design is based on the average temperature difference of 480 °C, assuming the heat sink temperature equal to the ambient temperature of that place. In presence of sun, Fresnel lenses of a specially designed hybrid capsule capture solar energy and concentrate them to provide necessary heat for the operation of the engine. In absence of the sun, required heat is provided by the thermo-chem- ical energy stored in Zeolite pellets. Working methodologies, modelling and simulation of the proposed system along with analyses of the obtained simulated results are presented in this paper. Possible perfor- mance of the scheme at different global positions for different period of a year has also been investigated. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Electricity has become the fundamental necessity of modern world. More than 80% of electrical power is generated from fossil fuels [1]. The fixed reserve and the harmful effects of these conven- tional fuels have compelled researchers to think of alternatives. Scientists consider renewable energy resources as the best substi- tute of the trendy energy sources [2,3]. Amongst all the inexhaust- ible resources, solar energy is most abundant in terms of generating capability and a lot of work has been done to explore its potential on earth [4–7]. Most of the work, on solar energy for electricity generation, is based on photovoltaic (PV) with battery storage [2,8–11]. This paper presents a method of solar-thermal power generating system with thermo-chemical storage (magne- sium sulphate impregnated Zeolite pellet). The thermo-chemical storage alleviates most of the shortcomings of traditional battery storage system like heavy weight, fixed life span, more charging time than discharging time, etc. In the proposed scheme, solar tracking system, which is an indispensable part of a PV technology, is replaced by a hybrid capsule consisting of glass and Fresnel lens reducing the complexity and additional energy consumption thereby decreasing expenses. Stirling engine is the heart of the plant that converts the ther- mal energy in solar irradiance into mechanical energy. Stirling engine is an external combustion engine developed by Dr. Robert Stirling in 1816 [12,13]. It is a closed-cycle regenerative machine that operates on cyclic compression and expansion of the working fluid [13]. Stirling engine has higher thermal efficiency than Rankine cycle based system and is reported that it is cheaper than PV unit of small capacity [14]. Some other advantages of Stirling engine are multi-fuel capability, low noise, low fuel consumption, capability of using various fuel sources, etc. [15]. Due to the pro- nounced merits of Stirling engine, many researchers have shown interest in it. Can et al. [16] developed a Beta type Stirling engine using crank mechanism while, Aksoy and Cinar [17] performed theoretical investigation on kinematic and thermodynamic analy- sis of a beta type Stirling engine with rhombic-drive mechanism. Abbas et al. worked with dish Stirling technology with hydrogen as working fluid [18], on the other hand, Moghadam et al. [19] pro- posed a solar dish micro-combined heat and power (CHP) system and carried out its 3E (energy, environment and economic) based analysis. In [20], a delta-T Stirling engine have been developed and experimented by Boutammachte et al. under laboratory and field condition, conversely, an unconventional liquid piston Stirling engine pump was proposed by Van de Ven in [21] which was sup- posed to closely match the ideal engine cycle. Solmaz and Karabu- lut [22] explored the performance of a Stirling engine with a lever controlled displacer driving mechanism by comparing it with a rhombic-drive engine whereas, Karabulut et al. [23] carried out an experimental test on a similar system and presented the results. In the system, heat was supplied by liquefied petroleum gas (LPG) burner. The maximum power of 183 W was achieved with hot end http://dx.doi.org/10.1016/j.enconman.2014.06.030 0196-8904/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +91 9436325638/9436582874. E-mail addresses: shantanu.acharya1@gmail.com (S. Acharya), subhadeep_ bhattacharjee@yahoo.co.in (S. Bhattacharjee). Energy Conversion and Management 86 (2014) 901–915 Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman