Study of a low-temperature Stirling engine driven by a rhombic drive mechanism

Abstract

Accurate and precisess estimation of spatio-temporal variability of solar radiation is critical. Some commonly used models evaluate this variability using methods in which the data required for estimating atmospheric attenuation may not be easily accessible for some study areas. Here, a daily solar radiation estimation method which uses ambient air temperature, a Digital Elevation Model, time of year, and monthly radiation estimates from Solar Analyst model has been proposed. The objective was to use air temperature-based empirical models for atmospheric transmissivity and diffuse fractions to vary total monthly radiation estimation from Solar Analyst, and then calculate total daily radiation as a fraction of total monthly radiation by applying a daily transmissivity-based ratio, as air temperature data are readily available at most locations on the planet. Results revealed that daily solar radiation can be estimated very well, with Mean Absolute Bias Error of around 40-53 W m −2 or Mean Bias Error of ± 10%, under all sky conditions at seven sites in diverse climate regions, using significantly less input data. The presented method is an improvement over previously used methods with Mean Bias Error of under 10% but more input parameters. Furthermore, the hourly solar radiation values can be calculated using the presented method using the ratio between daily and hourly radiation, for example from literature values and estimated daily insolation. The result also showed that the method is more useful for those stations with substantially higher numbers of sunny days than cloudy or partly cloudy days because the uncertainty of the model decreased from cloudy to sunny sky conditions. The implemented Digital Elevation Models environment of this method makes it applicable in many studies that need spatial estimation of solar radiation, especially for solar energy generation projects. Keywords Solar radiation · Digital elevation model · Solar analyst · Atmospheric transmissivity · Air temperature Abbreviations

Optimization of Low Temperature Differential Stirling Engine Regenerator Design

“…The indicated work is calculated based on the variation of the total volume and the instantaneous pressure. Two Schmidt hypothesis were adopted; the harmonic variation of engine volumes, and the uniform pressure inside the engine [23]. Our machine can be represented as in Figure 2.…”

“…Applying the ideal gas law, we can write: (12) Using Schmidt theory for our beta type Stirling engine, we find the following expression of instantaneous pressure, according to engine flywheel rotation angle θ [23]:…”

Design, Manufacture and Measurements of Beta-Type Stirling Engine with Rhombic Drive Mechanism

“…Kwankaomeng, S., et al [5] presented a design and manufacture process of a rhombic drive based on the assumptions made to simplify the theoretical modeling of the system causing inaccurate results compared to experimental data. El Hassani, H., et al [6] studied parameter effect on a low temperature solar Stirling engine driven by a rhombic drive mechanism using theoretical analysis to investigate the variation of the machine spaces and power using thermodynamic analysis and Schmidt's theory. The minimum values and directions about realizing the optimal phase angle were suggested for optimization of the rhombic drive mechanism and this increased power about 50%.…”

“…The ideal Stirling engine has advantages of high thermal efficiency, fewer emissions and being noiseless. In general, Stirling engines are available in three main types of configuration as follows [5] [6]:…”