Polygeneration microgrids: A viable solution in remote areas for supplying power,potable water and hydrogen as transportation fuel

This paper presents the concept and the design of a hybrid renewable energy polygeneration microgrid along with its technical and economical evaluation. The energy of the sun and the wind is harvested by photovoltaics and a wind turbine. Besides that, the components of the microgrid include a battery bank, a Proton Exchange Membrane (PEM) fuel cell, a PEM electrolyzer, a metal hydride tank, a reverse osmosis desalination unit using energy recovery and a control system. The microgrid covers the electricity, transport and water needs and thus its products are power, hydrogen as transportation fuel and potable water through desalination. Hydrogen and the desalinated water also act as medium to long term seasonal storage. A design tool based on TRNSYS 16, GenOpt 2.0 and TRNOPT was developed using Particle Swarm Optimization method. The economic evaluation of the concept was based on the discounting cash flow approach. The Monte Carlo Simulation method was used in order to take uncertainty into account. A technically feasible polygeneration microgrid adapted to a small island is financially profitable with a probability of 90% for the present and 100% at the medium term.     

基于TRNSYS平台对蒸发冷却系统的分析

利用系统仿真软件TRNSYS,以兰州地区办公楼的某房间作为模型,对其在夏季运用蒸发冷却空调系统的降温和舒适性进行了分析.结果显示,在我国西部干热地区运用蒸发冷却系统不仅可以实现良好的降温效果和舒适性,而且是一种节能技术.     

Thermal stratification in small solar domestic storage tanks caused by draw-offs

Storage tanks with different cold water inlet devices for small Solar Domestic Hot Water (SDHW) systems are compared. The objective of the investigation is to reveal the impact of the cold water inlet device on the thermal stratification in two marketed tanks and to evaluate the possible enhancement in the annual system performance of small solar heating systems. Two different marketed inlet designs are compared, one connected to a small curved plate placed above the inlet tube, the other one connected to a much larger flat plate. The cold domestic water enters the stores in vertical direction from the bottom of the tanks. Temperature measurements were carried out for different operating conditions. It was shown that the thermal stratification inside the two tanks depends differently on the flow rate, the draw-off volume, as well as the initial temperature in the storage tank. To carry out system simulations, a multi-node storage model was used and expanded by an additional input variable to model the mixing behaviour depending on the operating conditions. The inlet device with a comparatively large plate compared to the less favourable design results in an increase of the solar fraction of about 1–3%-points in annual system simulations with a solar fraction of about 60% and fairly large domestic hot water flow rates. This corresponds to a reduction of the auxiliary energy supply of the solar heating system of about 3–7% (58–155 MJ/year) for the investigated solar domestic hot water system.     

基于TRNSYS的地源热泵复合系统运行策略的优化

利用TRNSYS瞬时仿真模拟软件建立地源热泵与冷却塔复合系统模型,模拟出夏热冬冷地区办公楼地源热泵复合系统长期运行情况。在理论分析和实测数据验证的基础上,考虑气象条件、冷却塔开启时间、土壤散热等因素,分析该地区办公建筑冷却塔与地源热泵联合运行的特点;提出制冷期办公建筑夜间开启冷却塔蓄冷、白天地源热泵正常运行的模式。     

兰州地区农宅太阳能低温辐射采暖TRNSYS模拟研究

利用TRNSYS软件,对兰州地区单层农村住宅进行太阳能低温地板辐射采暖的数值模拟。通过模拟数据分析探讨了太阳能低温地板辐射采暖在农村地区的可行性、舒适性以及兰州地区太阳辐射特点探讨了太阳能低温地板辐射采暖的优势,发挥建筑节能的特点。     

Comparison of annual energy performances with different ventilation methods for temperature and humidity control

Stratum ventilation has been proposed to accommodate elevated indoor temperatures recommended by governments in East Asia. TRNSYS is used for computation of the space cooling loads, sensible and latent, as well as system energy consumption. Typical configurations of an office, a classroom and a retail shop in Hong Kong are investigated. Desiccant dehumidification with and without solar assistance is utilized for the air treatment under displacement ventilation and stratum ventilation, while simple reheating is adopted under mixed ventilation. Compared with mixing ventilation and displacement ventilation, stratum ventilation derives its energy saving potential largely from the following five factors: the reduction in ventilation, dehumidification and transmission loads, prolonged free cooling period and increased the COP of the chillers. For the office, the year-round energy saving is found to be substantial at 20% and 40% without the need for solar energy provision when compared with displacement ventilation and mixing ventilation respectively. For the classroom and retail shop, the year-round energy saving is at about 25% and at least 37% with the aid of solar energy provision when compared with displacement ventilation and mixing ventilation respectively.     

基于TRNSYS的太阳能耦合燃料电池热电联产系统的模拟研究

文章建立了太阳能耦合燃料电池热电联产系统的TRNSYS模型。采用镇江地区的天气数据(太阳直射辐射强度和环境温度),模拟了该系统在各典型日的火用效率。得出热电联产系统的集热量、发电量及火用效率均随着太阳辐射强度的增强而提高的结论。基于此,将热电联产系统的生命周期成本设为优化目标,采用Hooke-Jeeves算法对关键运行参数进行优化。结果表明:当集热器面积为15 m²,单电池片数为60个,蓄热水箱容积为5 m²,太阳能电池板面积为5 m²时,可以获得最小的生命周期成本49.1万元,比常规模型降低11.7%;优化后的热电联产系统在典型日的火用效率为50%~57%,较常规热电联产系统提升50.0%~85.7%。     

Simulation of the thermal performance of a hybrid solar-assisted ground-source heat pump system in a school building

A hybrid solar-assisted ground-source heat pump (SAGSHP) system was designed, in the frame of an energy upgrade study, to serve as a heating system in a school building in Greece. The main scope of this study was to examine techniques to reduce the capacity of the heating equipment and to keep the primary energy consumption low. Simulations of the thermal performance of both the building and of five different heating system configurations were performed by using the TRNSYS software. The results are presented in this work and show that the hybrid SAGSHP system displays the lower primary energy consumption among the systems examined. A conventional ground-source heat pump system has the same primary energy consumption, while the heat pump’s capacity is double and the ground heat exchanger 2.5 times longer. This work also highlights the contribution of simulation tools to the design of complex heating systems with renewable energy sources.