Abstract

Sustained environmental pollution and energy crisis are constantly promoting the development of hybrid electric vehicles. Among many configurations, the power-split ones based on planetary gear have special advantages of energy saving potential and velocity conversion characteristics.[1] Thus it has attracted considerable attention in related fields. Power-split system based on dual-planetary gear provides a variety of energy flow modes,[2] so it is suitable for constructing a multi-mode hybrid power-system for hybrid electric commercial vehicles. In this paper, a power flow model for the vehicle with such configuration is constructed; the energy flow relationship is analyzed and optimized. The optimal power flow relationship can be used to guide the division of working modes of hybrid electric vehicles and also provided a model basis for further study of related energy management strategies.

Abstract

In this paper, study on a volumetric receiver which use for solar energy season storage and heating system. This type of volumetric receiver has a high heat capacity, so that volumetric receiver can be ensured under severe weather conditions. In order to provide a reference for design and modification of volumetric receiver, the heat transfer characteristics of the volumetric heat absorber are studied. The influence of extinction coefficient and wind speed on the heat transfer characteristics of the volumetric receiver is analyzed by single factor analysis.

Abstract

Resilience is used to assess the ability to maintain and recover system performance in an extreme weather, which is one of the most important performance indicators of smart grid. A model for evaluating the hurricane resilience of distribution network considering fault repair is proposed. First, the difference between toughness and reliability is described. Second, to perfect the resilience assessment and analysis method of distribution systems, a component failure probability model under hurricane condition is built, the latin hypercube sampling is used to reduce the failure scenes and a distribution network restoration model considering fault repair is established. Finally, a simulation verifies the validity and accuracy of the proposed approach in this article.

Abstract

The intermittent of wind power poses a challenge to operation security and stability of power system. The power grid has the potential to guide wind power to be accommodated in a wider geographical region, and its impact is more prominent in real-time dispatch and controlling. Considering the constraints of bus voltage and branch power flow, this paper focus on the of wind power accommodation capability (WPAC) of system and buses, the coupling relationship of the WPAC of different buses is analyzed. In order to assistant real-time dispatch, an evaluation method of WPAC in real-time dispatch considering security constraints of power grid is proposed, which transforms security constraints of power gird into bus output constraints, evaluates WPACs of the system and different buses at a certain period in real time dispatch. The reasonableness and effectiveness of the presented method is validated by case study.

Abstract

Hydrotreated Vegetable Oil (HVO) and Gas to Liquid fuel (GTL) are two renewable fuels without shortcoming as traditional renewable fuels such as FAME. This project aims to research macroscopic spray characteristics of HVO and GTL during both injection and post-injection periods at high ambient temperature and pressure. The work is conducted by experiments on a constant volume vessel (CVV) system at 1800 bar rail pressure, 10 bar and 40 bar ambient pressure and 600 K ambient temperature. Results indicate that HVO and GTL have similar average cone angle to standard diesel fuel (DF), whilst their spray tip penetration during injection and post-injection periods are both smaller than that of DF. Moreover, the two renewable fuels have faster evaporation at high ambient temperature compared with DF, and thus results in the reduction of spray tip penetration with sample time.

Abstract

In order to further study the effect of internal and external coils on the heating performance of fermenters, this paper studied the advantages and disadvantages of internal and external coil heating fermenters under different TS value materials and different ambient temperature conditions, and passed the total heat transfer coefficient. The heating rate, temperature uniformity and temperature control economy of the fermentation system compare the difference between the inner and outer coils. The results show that the ambient temperature has a great influence on the external coil; as the TS value increases, the inner coil heating rate is higher than the outer coil, but the tank temperature uniformity is lower than the outer coil.

Abstract

From the perspective of improvingenergy efficiency andthermal comfortof solar heating system, theactive solar heating systemunder different stragetiesis experimented in Hezuo city, Gansu province, China in the heating season of 2018 to 2019. The conclusions revealthat without increasing energy consumption, smaller the supplyduration and the intermittent duration, higher the heating efficiency. The living room air temperature,average heating rate and cooling rateof the kang surfacetemperature change more slowly. Regardingthe on-off time ratio of 50%, the optimal strategy of the system areto combine 15/15min mode with variable flow mode B to ensure the systemownhigh energy efficiency and well thermal comfort.

Abstract

Winter heating, as a basic need of the public, takes great effects on living habits and living level. In Gannan Tibetan Autonomous Prefecture, winter is cold and winter heating lasts for 7 months. Passive solar building technology has been advocated and spread for energy-saving and living standard improving since 1970s. At present, coal and dry cow manure are usually burned in stove for heating and indoor comfort is still unknown for the passive solar building. Considering clean heating with solar energy, an active solar heating system was developed in a passive solar building with low temperature floor irradiator and water heating Kang and indoor comfort of a passive solar building with active solar heating was compared to that with stove heating by on-site experiments and PMV-PPD method. The experimental results show that, in a whole heating season, the indoor temperature of five sevenths days meet the Standard of GB50785-2012 and humidity always meets the Standard and the concentrations of CO, SO2, NO2, PM10, PM2.5 and CO2 are always below the Standard Values in GBT18883-2002 in the passive solar building with active solar heating, while in the passive solar building with stove heating, the indoor temperature usually does not meet the Standard and the concentrations of CO, SO2, NO2, CO2, PM2.5 and PM10 are always higher than that of the passive solar building with active solar heating and the concentrations of PM2.5 and PM10 are always higher than the Standard Values in GBT18883-2002. According to the evaluation of PMV-PPD index and IAQ index, active solar heating show more favorable performances than stove heating in a passive solar building. Hence, in cold Tibetan areas, it is promising for active solar heating to take the place of stove heating in aspects of energy-saving and indoor air quality improving.

Abstract

This paper proposed a new configuration of heat recovery cycle integrating PTES with ORC. A thermodynamic model was built to study the charging process of PTES. A parametric analysis has been conducted to evaluate the performance of the charging process. This paper defined the efficiency of the charging process of PTES with/without ORC. The isentropic efficiency of compressor/expander, the pressure ratio, and the designed temperature have been chosen to analyze the performance of the charging process. The proposed solution can be potentially used to improve the round-trip efficiency of PTES.

Abstract

Solar energy storage has vast applications in a wide range, and nanoparticles and metal foam can be used to improve energy storage density and heat transfer rate in a storage system. In this study, solar salt, nano-salt (solar salt seeded with 2 wt. % aluminium oxide (Al2O3) nanopowder) and nano-salt/copper foam composite were used as storage media, and the thermal performances during heat storage/retrieval processes were investigated with a pilot experimental rig. The temperature distributions of the PCMs at radial, theta, and axial locations were measured. The results show that Al2O3 nanopowder can slightly improve the heat transfer of the nano-salt, while the system encapsulated with the nano-salt/copper foam composite can be significantly enhanced, e.g. the time-duration of the charging process can be reduced by about 74.5%, compared to that of pure salt. Theoretical analysis also revealed the heat transfer domination by temperature distribution. The heat storage power can reach 200.27 kW/m3 when nanosalt/copper foam composite was used.