Micro newcomen steam engine using two-phase working fluid

Energy 36 (2011) 917e921

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Energy
journal homepage: www.elsevier.com/locate/energy

Micro Newcomen steam engine using two-phase working fluid
Yang Wang, Zhijun Zhou*, Junhu Zhou, Jianzhong Liu, Zhihua Wang, Kefa Cen
State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, Zhejiang, China

article info

abstractArticle history:
Received 4 March 2010
Received in revised form
8 December 2010
Accepted 11 December 2010
Available online 21 January 2011

A micro steam engine is developed based on Newcomen steam engine. In the micro engine, a flexible
ripple tube takes the place of piston and cylinder, to overcome the serious problems of friction and
leakage in micro scale. We use two-phase octane asworking fluid of the micro engine, because twophase octane has higher power density than gaseous one. The micro engine is tested under different
operational conditions to investigate its performance. It produces a maximum net mechanical work of
0.405 J per cycle with an efficiency of 2.58%. This experiment proves the feasibility of the micro steam
engine.
Ó 2010 Elsevier Ltd. All rightsreserved.

Keywords:
Ripple tube
Micro scale
Newcomen steam engine
Thermodynamic cycle

1. Introduction
The power of portable electronic devices, such as laptops,
cellular phones, is supplied by battery. Its energy densities are less
than 0.5 MJ/kg [1], thus limit the operation period. Micro power
system converts chemical energy of hydrocarbon fuels to electricity
directly, thus has higherpower density [2]. Its performance will
excel the conventional battery, if only its efficiency is higher than
1% [3e5]. Although fuel cells have higher efficiency than micro
power system [6]. They are made of expensive Pt material and only
adapt a few kinds of fuel with high purity.
The first micro gas turbine based on Micro Electro Mechanical
System (MEMS) technology was suggested inMassachusetts
Institute of Technology (MIT) in 1996 [7]. Then, Jan Peirs developed
a single-stage axial micro turbine driven by compressed air [1].
Besides micro turbine, internal combustion micro engine was also
proposed [8]. For example, C.H. Lee produced a micro Wankel
engine driven by CO2 [9]. Zhang Shimin fabricated a prototype of
micro free-piston swing engine [10]. Homogeneous ChargeCompression Ignition (HCCI) was also proposed to improve the
micro engine’s performance [11e13]. To overcome the serious
problems of friction and leakage between mechanical parts in
micro engine [14], T. Geng fabricated a micro pulsejet [15].
S. Whalen developed a novel P3 engine, made of an elastic
membrane [16,17]. Energy converters based on thermoelectric or
thermophotovoltaic material were alsoproposed [2,18e20].

* Corresponding author. Tel./fax: þ86 571 87951616.
E-mail address: zhouzj@cmee.zju.edu.cn (Z. Zhou).
0360-5442/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.energy.2010.12.019

Technology of manufacture limits the development of micro
engine. The low machining accuracy causes friction and abrasion
of the mechanical parts. The leakage alsoinduces low efficiency.
These problems cause poor performance and instability of micro
engine [1].
In this paper, a new micro steam engine is proposed. We try to
take the place of piston and cylinder of engine with a flexible ripple
tube. It works as one monolithic part, thus solves the problems of
friction and leakage. In the experiment, we test the micro engine
prototype under differentoperational conditions, to prove its
feasibility.

2. Experimental system
2.1. Experimental facility
The prototype engine is developed based on Newcomen steam
engine. For experimental convenience, the engine is powered by
electricity instead of fuel. A block diagram of the facility is shown in
Fig. 1. The experimental system has a loader and a heater installed,
which exchange mechanical...