Techno-economic appraisal of a dish/stirling solar power plant in Greece based on an innovative solar concentrator formed by elastic film

As the environmental problems caused by the use of conventional fuels have risen significantly and due to the increase in fossil fuel prices, the importance of reducing society dependence on non-renewable energy sources becomes more and more urgent. It is clear that this could only happen by switching to extensive use of clean energy sources such as renewable energy sources. In this paper a technical feasibility and economic viability study of a dish/Stirling solar power plant in Greece is presented. The proposed power plant uses Dish/Stirling technology and has nominal power 10 MW. The proposed solar concentrator system consists of a primary mirror, formed by elastic film, used to focus the sun's rays onto a secondary mirror which then deviates this radiation into the receiver (Stirling engine). TRNSYS program was developed to simulate Dish/Stirling power plant operation in order to investigate its performance in Greece. The simulation predicted that the proposed power plant could produce 11.19 GWh annually. Project investment cost is approximately 27,000,000 €, while payback is achieved after 16 years of operation. The total profit at the end of the analysis period of 25 years is estimated to be 25,500,000 €.     

Numerical model and experimental validation of heat storage with phase change materials

This paper describes the numeric model developed to simulate heat transfer in phase change materials (PCM) plunged in water tank storage. This model, based on the enthalpy approach, takes into account the conduction and the convection into PCM as well as at the interface between PCM and water of the storage. Furthermore, hysterisis and subcooling are also included. This model has been implemented in an existing TRNSYS type of water tank storage. It allows the simulation of a water storage tank filled with PCM modules made of different materials and different shapes such as cylinders, plates or spheres bed. Comparisons between measurements and simulations has been undertake to evaluate the potential of this model.     

Dynamical building simulation: A low order model for thermal bridges losses

Thermal bridges losses represent an increasing part of heat losses owing to significant three-dimensional heat transfer characteristics in modern buildings, but one-dimensional models are used in most simulation software for thermal analyses to simplify the calculations.State model reduction techniques were used to develop low-order three-dimensional heat transfer model for additional losses of thermal bridges, which is efficient and accuracy. Coupling this technique with traditional one-dimensional model for walls losses, it is possible to reduce a large amount of time simulations.Low-order model was validated from frequency response and time-domain output. And the effect of this model was shown with its implementation in software “TRNSYS”.     

太阳能-地源热泵系统的运行模拟

以济南市某工程为例,使用DeST软件对该工程进行年逐时负荷模拟,得到冷负荷峰值为313.3 kW,热负荷峰值为293.7 kW,累计年排热量为166 451 kW·h,累计年提热量为210 380 kW·h,热不平衡率为20.88%。利用TRNSYS软件建立了太阳能-地源热泵系统动态模型,并进行模拟分析。当地土壤初始温度均为15.3℃,复合系统的模拟结果显示系统运行20年,地温均值一直保持在14.8~16.4℃的稳定范围内。研究表明:太阳能-地源热泵复合系统具有良好的蓄热能力,提高了太阳能利用率,可有效解决寒冷地区地源热泵的冷热不平衡问题,是解决严寒地区供暖问题的一个重要途径。     

基于TRNSYS的土壤源热泵热平衡问题的影响因素分析

夏热冬冷这种冷负荷占优地区,若由土壤源热泵系统承担所有的空调负荷,则会造成全年土壤取放热量的不平衡,从而出现常年运行后土壤温度的逐渐上升,降低系统夏季的运行效率,不利于系统持续稳定高效的运行。为此首先利用模拟软件TRNSYS搭建土壤源热泵系统模型,对土壤源热泵系统长期运行性能进行模拟分析,从冬夏累计负荷比、埋管间距、埋管深度、土壤导热系数、回填料导热系数这几个影响因素出发,研究土壤源热泵长期运行的热平衡问题,以期对土壤源热泵系统的合理应用和发展提供支持。     

某项目景观水池防冻负荷模拟和节能优化

针对一个实际工程问题,分析了室外景观水池与外界的热交换过程,介绍了水池非稳态换热过程数值模型,利用该数值模型在TRNSYS平台下建立了水池换热模块,搭建了水池换热系统模型,对冬季景观水池温度进行了全年动态模拟,确定了防冻加热负荷.在此基础上,提出了采用地埋管直接换热的系统节能方案,在原模型中加入了地埋管换热器模块,模拟了该系统的水温和换热量,并对地埋管的热平衡进行了模拟验证.该水池换热模块适用于各类室外较浅的静水体的动态换热计算问题,采用的计算方法和优化方案为类似项目提供了参考.     

土壤源热泵变流量系统的长期运行特性研究

在TRNSYS仿真模拟软件的基础上,对其中的变速泵模拟进行了优化,并用实验值验证模型。分别建立定流量和变流量系统的仿真模型,并进行长期模拟。模拟结果得到15年的水泵、热泵机组全年的能耗,分别讨论了制冷期、制热期的能耗情况,并从15年的土壤平均温度变化讨论定流量与变流量对埋管区域热环境的影响。     

土壤源热泵系统建模及运行参数优化

地埋管换热器的优越性能在当今社会越来越受到重视,在供暖、烘干、能源互补利用方面有广阔的前景。本文基于TRNSYS软件建立上海某建筑的模型系统设计,并介绍了建筑负荷模拟的过程、冷却塔串联和并联方式的模拟计算。针对上海的天气情况、土壤源温度的变化作为原始变量进行了模拟分析,比较得出性能好方案,最后进行较好方案的继续优化。     

太阳能-地源热泵与热网互补供暖系统的仿真性能研究

以沈阳地区典型民用住宅建筑为例,对太阳能-地源热泵与热网互补供暖系统进行仿真研究。利用TRNSYS软件,建立太阳能-地源热泵与热网互补供暖系统仿真模型和地源热泵与热网互补供暖系统仿真模型,对2种系统的蒸发器进出水温度、热泵机组COP,及热网加热量进行对比分析,结果表明:太阳能-地源热泵与热网互补供暖系统相比地源热泵与热网互补供暖系统的平均出水温度提高了50.41%;平均进水温度提高了53.08%;平均COP由3.167增加到4.65;热网运行时间由1540h增加到2032h;热网供暖季的平均换热量由114566.62kJ/h减少到101257.27kJ/h。