Effect of finite heat input on the power performance of micro heat engines

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Description/Abstract

Micro heat engines have attracted considerable interest in recent years for their potential exploitation as
micro power sources in microsystems and portable devices. Thermodynamic modeling can predict the
theoretical performance that can be potentially achieved by micro heat engine designs. An appropriate
model can not only provide key information at the design stage but also indicate the potential room for
improvement in existing micro heat engines. However, there are few models reported to date which are
suitable for evaluating the power performance of micro heat engines. This paper presents a new thermodynamic
model for determining the theoretical limit of power performance of micro heat engines
with consideration to finite heat input and heat leakage. By matching the model components to those of
a representative heat engine layout, the theoretical power, power density, and thermal efficiency
achievable for a micro heat engine can be obtained for a given set of design parameters. The effects of key
design parameters such as length and thermal conductivity of the engine material on these theoretical
outputs are also investigated. Possible trade-offs among these performance objectives are discussed.
Performance results derived from the developed model are compared with those of a working micro heat
engine (P3) as an example.