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Abstract A Triangle Cycle with a piston engine expansion unit is used to convert low temperature heat into electrical energy. In this process, the isentropic efficiency of the expansion unit is considered to be unknown, and a theoretical approach for the calculation of isentropic efficiency is presented. A number of influences are taken into account – dead volume, residual mass, liquid injection performance and wall heat transfer. Various working fluids are investigated in a wide range of temperatures (333K–573K), engine speeds (5 Hz–30 Hz) and stroke volumes (0.1 L–50 L). The isentropic efficiency of water as working fluid is in the range of 0.75–0.88 and drops significantly for high stroke volumes and engine speeds. In general, injection mass has the most impact on isentropic efficiency because it influences dead volume and injection performance. The injection mass increases with vapor density and therefore is significantly influenced by working fluid and temperatures. The Triangle Cycle is compared with Organic Rankine Cycles by using determined isentropic efficiency. The exergetic efficiency of the Triangle Cycle using water is up to 35–70% higher than that of supercritical Organic Rankine Cycles in situations with a heat source temperature of up to 450K.

Abstract Based on the design concept of a fourth-generation smart pipe network system, this paper innovatively proposes a new TOTS (Two-supply/One-return, triple pipe structure) arrangement method for district heating systems. Moreover, to accurately predict the heat loss due to the pipeline operation of the multi-pipe system, based on the multipole calculation method, a new heat loss theoretical analytical model for the TOTS was created; additionally, a corresponding three-dimensional numerical simulation model was established, which was analyzed and numerically solved. The results showed that in comparison with thermal loss data measured by Danfoss et al., the above analytical and numerical models have a high accuracy, and the deviation is within 2%. Additionally, through calculations, it was found that the distance between the heating pipes is an important factor that affects the total heat loss from the new multi-control heating system and the actual heat exchange between pipes.

A balance between industrial pollution and economic growth becomes a major policy issue to attain a sustainable society in the world. To discuss the problem from economics and business perspectives, this study proposes a new use of DEA (Data Envelopment Analysis) as a methodology for unified (operational and environmental) assessment. A unique feature of the proposed approach is that it separates outputs into desirable and undesirable categories. Such separation is important because energy industries usually produce both desirable and undesirable outputs. This study discusses how to unify the two types of outputs under natural and managerial disposability. The proposed DEA approach evaluates various organizations by the three efficiency measures such as OE (Operational Efficiency), UEN (Unified Efficiency under Natural disposability) and UENM (Unified Efficiency under Natural and Managerial disposability). An important feature of UENM is that it separates inputs into two categories and unifies them under the two disposability concepts in addition to the proposed output separation and unification. This study incorporates an amount of capital assets for technology innovation, as one of the two input group, into the measurement of UENM. Then, it compares UENM with the other two efficiency measures. This study is the first research effort in which DEA has an analytical capability to quantify the importance of investment on capital assets for technology innovation. To confirm the practicality of the proposed approach, this study applies the three efficiency measures to a data set regarding manufacturing and non-manufacturing industries of 47 prefectures in Japan. This study empirically confirms the validity of Porter hypothesis in Japanese manufacturing industries, so implying that environmental regulation has been effective for betterment on the performance of Japanese manufacturing industries. Another important finding is that the emission of greenhouse gases is a main source of unified inefficiency in the two groups of industries. Therefore, Japanese industries, examined in this study, need to make their efforts to reduce the greenhouse gas emissions and air pollution substances by investing in capital assets for technology innovation.

Abstract We present estimates for the effective oxidation rates of methane over a wide range of equivalence ratios using Ar as primary diluent and CO or H 2 O as additives. The rate of disappearance of methane has been monitored in a fuel-rich CH 4 O 2 Ar mixture by direct measurements of the change in transmission for He-Ne laser radiation at 3.392 μ behind reflected shock waves. The rate of formation of water with time has been obtained in independent absolute i.r. emission measurements near 6.75 μ on stoichiometric CH 4 O 2 Ar mixtures with and without added water. We have found empirically that a number of data correlations may be used and that the overall rates of disappearance of CH 4 and of formation of H 2 O were the same during the post-induction period behind reflected shock waves. The rates of concentration changes with time to which we refer are average rates observed during the post-induction periods. The temperatures ( T max ) for which the oxygen-atom concentrations are a relative maximum were found to be close to the arithmetic means between the initial temperatures ( T 5 ) behind reflected shock fronts and the final equilibrium temperatures. The numerical values found for the correlation parameters as functions of the temperature during the post-induction oxidation are not sensitive to the prior admixture of CO or H 2 O but vary with mixture ratio. The overall methane conversion rates are directly useful in defining burner designs for the utilization of highly diluted mixtures (i.e. low-Btu gas systems) containing primarily CH 4 . Our results are not applicable to low-Btu gas mixtures containing such reactive species as H 2 or NH 3 .

Abstract The aim of this study is to examine the potential seasonality of China's crude oil import in hope of helping the stakeholders with inventory control and production planning. In order to proximately achieve the goal, X-12-ARIMA method was used to adjust the monthly series and the quarterly series of China's crude oil net import in the last 16 years. The results show that the quarterly series is better than the monthly series in terms of seasonality adjustment; the seasonal factors tend to be positive in spring and summer quarters while negative in fall and winter quarters; and the former three seasonal factors are growing stronger while the winter factor weaker in recent years.

Abstract This paper uses quantile regression to demonstrate how electricity price distributions are linked to fundamental supply and demand variables. It investigates the California electricity market (zone SP15) for selected trading hours using data from January 8, 2013 to September 24, 2016. The approach quantifies a non-linear relationship between the fundamentals and electricity prices, just as predicted by the merit order curve. Natural gas, greenhouse gas allowance prices and load all have a positive effect on electricity prices, with the effect increasing with the quantiles. In contrast, solar production and wind production both have a negative effect on electricity prices. The effect of solar production increases with quantiles, whereas the effect of wind production decreases with quantiles. This paper also includes a stress testing case study in which a producer faces the risk of high solar and wind production, and investigates the effect on the lower tail of the price distribution. Overall, the results demonstrate how the proposed approach can be a helpful risk management tool for participants in the electricity market.