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Abstract: There are many kinds of methods to estimate the energy requirement or fuel consumption in the optimal design and minimize the life cost of a building. The bin method is one of the most popular ways to estimate the energy performance of a building, which is based on the hourly-based outdoor dry-bulb temperatures of all days in a whole year. There is lack of information about the bin weather data in China. In this paper, the ambient temperature bin data for 26 cities in China are generated. Based on the method used in this paper, the bin data can be calculated with the long-term daily weather record or TMY weather data, the deviation between them is acceptable. The bin data given in this paper may have the positive impact on building energy conservation in China. [Copyright &y& Elsevier]

Abstract: The bin method, as one of the well known and simple steady state methods used to predict heating and cooling energy consumption of buildings, requires reliable and detailed bin data. Since the long term hourly temperature records are not available in China, there is a lack of bin weather data for study and use. In order to keep the bin method practical in China, a stochastic model using only the daily maximum and minimum temperatures to generate bin weather data was established and tested by applying one year of measured hourly ambient temperature data in Nanjing, China. By comparison with the measured values, the bin weather data generated by the model shows adequate accuracy. This stochastic model can be used to estimate the bin weather data in areas, especially in China, where the long term hourly temperature records are missing or not available. [Copyright &y& Elsevier]

Solar radiation and sunshine duration data from 69 meteorological stations in China was used to develop the formula for estimating the monthly average daily global radiation on a horizontal surface. Several models and correlations that embrace such variables as the fraction of sunshine duration, the latitude and the altitude have been selected, tested and compared to decide which model is recommended on the basis of statistical error tests. In this study, using the relative duration of sunshine as a single independent variable, the most accurate equation that is expressed in a third order form was obtained for each station. The results show that the coefficients are site dependent. Subsequently, taking the radiation data and geographical parameters at all 69 stations as reference, a countrywide general equation was established. Compared with the equation using the relative duration of sunshine as a single independent variable, the general equation shows relatively lower accuracy, but estimating the global solar radiation by this equation has proved sufficiently reliable. This equation can be used to estimate the monthly average daily global radiation in areas where the radiation data is missing or not available, so that a geographical distribution of global solar radiation across the country may be obtained. [Copyright &y& Elsevier]

In this paper, a wave energy harvesting system based on the double-wing flywheel is proposed for extending the work life of unmanned surface vessels (USVs). The system can be divided into four modules: wave energy capture module, motion conversion module, electromagnetic transducer module, and circuit module. The device is installed inside the USV. The wave energy capture module captures the energy of USV vibration. The vibrating mass block drives the nut in the motion conversion module to vibrate up and down and then drives the screw to rotate. Through the one-way bearing on the screw, the bidirectional rotational motion of the screw is converted into the relative one-way rotation of the electromagnetic transducer module. The electromagnetic transducer module mainly consists of a magnet flywheel and coil flywheel, both of which are driven by the motion conversion to one-way rotate relatively. The relatively-one-way rotation of the electromagnetic transducer module improves the power generation efficiency of the device. The generated electrical energy will be passed through the circuit module to store in the supercapacitor and eventually power the sensor. A prototype was fabricated, and the power generation performance of the system was evaluated by bench test under different sinusoidal excitations. Analyzing the experimental results, it was found that the average power output is 40.24 W, given 1.0 Hz-80 mm sinusoidal vibration input. The comparative experiments show that the device with the double-wing flywheel mechanism increases the maximum average power by 51.64% compared to the non-MMR device. The USV sensors and the operating time analysis show that the system can support sensors to operate intermittently, which shows the potential of the wave energy harvesting device for use on USV. [Display omitted] • A double-wing flywheel-based wave energy harvesting system is proposed for USV. • An efficient double-wing flywheel electromagnetic transducer is proposed. • Dynamics model of double-wing flywheel electromagnetic transducer. • The output power is increased by 51.64% by the double-wing flywheel mechanism. Unmanned surface vessels (USVs) are increasingly used in environmental protection, safe search, rescue, and maritime investigations. These USVs are generally battery or diesel-powered for sailing, and the limited size of USVs results in a lower working life of USVs. This paper proposes a wave energy harvesting system for USVs based on a double-wing flywheel. This system is installed in the hull of the USV and converts the wave energy that causes the USV to vibrate into electrical power. The system can be divided into four modules: wave energy capture module, motion conversion module, electromagnetic transducer module, and circuit module. The wave energy capture module captures the mechanical energy of USV vibration caused by waves and the change of driving state and converts it into the mechanical energy of the mass block vibration. The motion conversion module uses a screw-nut mechanism and the double-wing flywheel mechanism to convert the reciprocating vibrations of the mass block into the relative one-way rotation of the magnet flywheel and the coil flywheel. The electromagnetic transducer module converts the mechanical energy of flywheels into electrical energy and transmits it to the circuit module. The circuit module rectifies the current and stores the electrical energy in a supercapacitor, eventually used to power various sensors. Simulations and experiments were conducted on the proposed wave energy harvesting system. MTS bench experiments confirm a 51.64% increase in energy harvesting power than an energy harvesting device without a mechanical motion rectifier (MMR). Data transfer experiments show that the system can capture wave energy to drive temperature and humidity sensors for data transmission. The results show that the energy harvesting system can be practically applied to USVs to improve their service life. [ABSTRACT FROM AUTHOR]

The grooves of notches of hydraulic spool valves are usually designed into various shapes for their desired flow characteristics. The aim of this paper is to clarify the effects of the groove shape on the flow characteristics through computational fluid dynamics (CFD) and experimental investigations. The RNG k-ε turbulence model is used to simulate the pressure distributions of the flow fields inside three notches with their corresponding typical structural grooves in order to analyze the changes of restricted locations along with the openings and, furthermore, to calculate the flow areas of the notches. The accuracy of the employed model is demonstrated by comparing the computational results with the experimental data. Additionally, the flow rate vs. pressure drop data obtained from the experiment is fitted by least square method. On this basis, the discharge coefficient as a function of groove geometry, flow condition, fitting coefficients and its stable value is deduced, proving to be quite consistent with the experimental result. Thanks to the jet flow angles estimated by CFD simulation, the steady flow forces are calculated, which show good agreement with the experimental results except for some small differences. Finally, the throttling stiffness of the three notches is investigated, with that of divergent U-shape groove falls between spheroid-shape groove and triangle-shape groove. Similar results are found for steady flow force. The results indicate that the groove shape has significant effects on the flow characteristics (flow area, discharge characteristic, jet flow angle, steady flow force and throttling stiffness) of spool valve. [ABSTRACT FROM AUTHOR]