Rana Shubhashis, Pal P S, Saha Arnab, Jayannavar A M
Institute of Physics, Sachivalaya Marg, Bhubaneswar-751005, India.
Institut för Theoretische Physik II, Weiche Materie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Oct;90(4):042146. doi: 10.1103/PhysRevE.90.042146. Epub 2014 Oct 30.
We have performed an extensive analysis of a single-particle stochastic heat engine constructed by manipulating a Brownian particle in a time-dependent harmonic potential. The cycle consists of two isothermal steps at different temperatures and two adiabatic steps similar to that of a Carnot engine. The engine shows qualitative differences in inertial and overdamped regimes. All the thermodynamic quantities, including efficiency, exhibit strong fluctuations in a time periodic steady state. The fluctuations of stochastic efficiency dominate over the mean values even in the quasistatic regime. Interestingly, our system acts as an engine provided the temperature difference between the two reservoirs is greater than a finite critical value which in turn depends on the cycle time and other system parameters. This is supported by our analytical results carried out in the quasistatic regime. Our system works more reliably as an engine for large cycle times. By studying various model systems, we observe that the operational characteristics are model dependent. Our results clearly rule out any universal relation between efficiency at maximum power and temperature of the baths. We have also verified fluctuation relations for heat engines in time periodic steady state.
我们对通过在随时间变化的谐振势中操纵布朗粒子构建的单粒子随机热机进行了广泛分析。该循环由两个不同温度下的等温步骤和两个类似于卡诺热机的绝热步骤组成。该热机在惯性和过阻尼状态下表现出质的差异。所有热力学量，包括效率，在时间周期稳态中都表现出强烈的涨落。即使在准静态状态下，随机效率的涨落也主导着平均值。有趣的是，只要两个热库之间的温差大于一个有限的临界值，我们的系统就充当热机，而该临界值又取决于循环时间和其他系统参数。这得到了我们在准静态状态下进行的分析结果的支持。对于大循环时间，我们的系统作为热机工作得更可靠。通过研究各种模型系统，我们观察到运行特性取决于模型。我们的结果明确排除了最大功率下的效率与热库温度之间的任何普遍关系。我们还验证了时间周期稳态下热机的涨落关系。
