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• A method to estimate optimal cycle time for adsorption chillers was developed. • The method takes into account the temperature conditions and design parameters. • Two mathematical expressions were empirically derived from 729 cases of simulations. • The estimated optimal cycle time has quite good agreement with the simulated result. The objective of this study is to construct mathematical expressions to estimate the optimum cycle time which maximizes the specific cooling power (SCP) of adsorption chillers with silica gel-water pair. The operating temperature conditions of hot water, cooling water and chilled water, as well as the design parameters such as heat transfer coefficient and heat capacities of the adsorbent heat exchanger and silica-gel, are taken into account to estimate the optimum cycle time. Totally 729 cases were examined to calculate the optimum cycle times from which mathematical expressions were derived. The empirical method reflecting the six parameters successfully estimates the optimum cycle time of the simulations with the coefficient of determination as high as 0.98. The performance for estimating the maximum SCP through the optimum cycle time is even better. [ABSTRACT FROM AUTHOR]

When the air conditioning and heating systems operate in low speed regions, the efficiency of inverter compressor is relatively low, owing to the reduction in motor efficiency. Nevertheless, the annual operating time of compressor is largely occupied by low speed regions. Hence, experimental and numerical analyses were conducted to improve compressor efficiency in these regions, and various pressure conditions were considered. The significant difference in the volumetric efficiency with compression ratios was observed through the experiments. To reduce the decrease in volumetric efficiency at high compression ratio, a geometric combination of the compression part was considered through a numerical analysis. The numerical results showed that the volumetric efficiency at small cylinder slenderness ratio was relatively high and increased by about 6.3% at a compression ratio of 7. Then the cooling capacity increased by 8.77%, while the input work showed a relatively small increase of 2.44%. [ABSTRACT FROM AUTHOR]

Reliability assessment has been used to evaluate the performance of pavement structures. However, probabilistic inversion analysis of pavement structure design has not yet been tested to determine the design parameters of the pavement performance function, given a specified reliability index. In this study, a limit state function numerical calculation and the inversion technique of the Nelder-Mead simplex algorithm were used to determine the design parameters for the pavement performance function. The method of moments was used to develop the forward limit state function, which was then compared to Monte Carlo simulations; the comparison indicated good agreement between the two methods. Additionally, several cases were studied to determine the design parameters of the pavement performance function for the reliability index specified in this study. The case studies indicated that the structure number significantly affected the pavement performance function. [ABSTRACT FROM AUTHOR]