基于TRNSYS的茯砖茶生产工艺能源系统节能环保特性研究

茯砖茶发酵、干燥过程中，烘房内温湿度稳定性和能源系统低能耗是保证茯砖茶品质与成本的重要因素。本文采用TRNSYS仿真与实验研究相结合的方法，对咸阳某茯砖茶厂实际使用的空气源热泵系统进行建模，通过研究各季节典型代表月烘房温湿度的波动情况，确定该空气源热泵系统在全年的运行状态是否满足工艺要求，在此基础上，对比了该系统在全年可运行季节代表月与该生产厂房早期使用的燃气锅炉系统的能耗仿真结果，对空气源热泵系统的节能与环保特性进行研究。结果表明：由于夏季送风质量流量过大且室外空气含湿量较高，7月烘房温湿度不满足工艺要求。热泵系统在1、4、10月的总标煤消耗量的平均值是锅炉系统的44.42%，平均CO2、SO2、NOx排放量分别为锅炉系统的34.13%、44.1%、40.60%。在茯砖茶发酵、干燥的过程中，相比于燃气锅炉系统，空气源热泵系统具有更好的节能与环保特性。     

西藏地区太阳能采暖建筑热工性能优化研究

西藏地区太阳能资源非常丰富且冬季温度低,该地区非常适合大面积推广太阳能采暖系统,以达到节能减排的目的。但是由于实际大部分太阳能采暖工程,忽略了建筑围护对太阳能主动式采暖系统初投资与运行费用的影响,造成了太阳能主动式采暖系统初投资过高、太阳能保证率低。为了分析建筑热工性能对太阳能主动式采暖系统的影响,笔者利用数值模拟方法,将建筑热工性能与主动式太阳能采暖系统作为一个整体进行计算分析,利用初投资费用最低与全寿命周期总费用最低两个目标函数,对主动式太阳能采暖建筑热工性能的保温性能进行优化。结果表明,提高建筑围护结构热工性能,不仅可以降低太阳能采暖建筑的采暖运行费用,而且可降低整个系统的初投资。     

Coupled simulation of BES-CFD and performance assessment of energy recovery ventilation system for office model

Thermal comfort and indoor air quality as well as the energy efficiency have been recognized as essential parts of sustainable building assessment. This work aims to analyze the energy conservation of the heat recovery ventilator and to investigate the effect of the air supply arrangement. Three types of mixing ventilation are chosen for the analysis of coupling ANSYS/FLUENT (a computational fluid dynamics (CFD) program) with TRNSYS (a building energy simulation (BES) software). The adoption of mutual complementary boundary conditions for CFD and BES provides more accurate and complete information of indoor air distribution and thermal performance in buildings. A typical office-space situated in a middle storey is chosen for the analysis. The office-space is equipped with air-conditioners on the ceiling. A heat recovery ventilation system directly supplies fresh air to the office space. Its thermal performance and indoor air distribution predicted by the coupled method are compared under three types of ventilation system. When the supply and return openings for ventilation are arranged on the ceiling, there is no critical difference between the predictions of the coupled method and BES on the energy consumption of HVAC because PID control is adopted for the supply air temperature of the occupied zone. On the other hand, approximately 21% discrepancy for the heat recovery estimation in the maximum between the simulated results of coupled method and BES-only can be obviously found in the floor air supply ventilation case. The discrepancy emphasizes the necessity of coupling CFD with BES when vertical air temperature gradient exists. Our future target is to estimate the optimum design of heat recovery ventilation system to control CO₂ concentration by adjusting flow rate of fresh air.     

Assessing heating and cooling demands of closed greenhouse systems in a cold climate

Reducing greenhouse gas emissions by providing non‐fossil fuel energy sources is imminently necessary. The area of particular interest in this paper is the agricultural greenhouse industry. In these structures, significant heating demands are present, especially in cold climates, and are typically met by combusting fossil fuels. In an effort towards a sustainable energy supply, the potential of closed greenhouse systems in a cold climate is explored. In these systems, natural ventilation for cooling and dehumidification is replaced with active systems, and the thermal energy removed can be re‐used, reducing the overall heating demand. A transient greenhouse model is created using TRNSYS software and validated with natural gas usage data from a reference greenhouse. The annual heating and cooling demands, effect of varying cover materials and potential for heat recovery ventilation are explored for the most concentrated greenhouse areas in Canada. Copyright © 2017 John Wiley & Sons, Ltd.     

Experimental and numerical analysis of seasonal solar‐energy storage in buildings

This paper presents seasonal‐energy storage of solar energy for the heating of buildings. We distinguish several types of seasonal storage, such as latent, sensible, and chemical storage, among which the thermochemical storage is used and analysed in this research. In the first part, a laboratory heat‐storage tank, which was made in the laboratory for heating, sanitary, and solar technology and air conditioning from the Faculty of Mechanical Engineering, University of Ljubljana, Slovenia, was presented. The experimental model was tested for charging and discharging mode. Two types of numerical models for sorption thermal‐energy storage exist, which are microscale and macroscale (integral). For microscale analysis, the analysis system (ANSYS) model can be used to simulate the behaviour in the adsorption reactor. On macroscale or integral scale, TRaNsient SYStem (TRNSYS) model was used to perform the operation of the storages on the yearly basis. In the second part the simulation of the underfloor heating system operation with a built‐in storage tank was carried out for two locations, Ljubljana and Portoro?. Furthermore, the comparison between a thermochemical and sensible‐heat storage was performed with TRNSYS and Excel software. In this comparison, the focus was on the surface parameters of the SCs and volume of the thermal‐storage tank for the coverage of the energy demand for selected building. With this analysis, we would like to show the advantage of the thermochemical storage system, to provide greater coverage of the energy demand for the operation of the building, compared with the seasonal sensible‐heat storage (SSHS). Such a heat‐storage technology could, in the future, be a key contributor to the more environmentally friendly and more sustainable way of delivering energy needs for buildings.     

夏热冬冷地区冷却塔—土壤耦合热泵过渡季蓄冷特性研究

本文针对夏热冬冷地区冷热负荷特性,提出了冷却塔—土壤耦合热泵过渡季土壤蓄冷模式,采用软件TRNSYS建立了冷却塔—土壤耦合热泵过渡季土壤蓄冷系统仿真模型,并利用该模型针对过渡季土壤蓄冷的两个主要影响因素进行了工况模拟分析,,在此基础上提出了冷却塔—土壤耦合热泵过渡季节土壤蓄冷的控制策略.本文力图通过上述研究探索出缓解夏热冬冷地区土壤源热泵系统全年热失衡问题、提高该系统运行效率的有效途径.     

Decentralised cooling in district heating network: Monitoring results and calibration of simulation model

This article presents the monitoring results of a thermally driven chiller (TDC) driven by district heat from a network supplied by a centralised combined heat and power (CHP) fired with municipal waste. The main objective of this article is to analyse the monitoring results obtained from the demonstration and calibrate a system model that is later used for parametric studies in order to find improved system design and control. The calibration of the system model was made in three stages and all the energy performance figures were within 4% of the measured values. Results show that the TDC system is capable of providing maximum thermal and electrical COP's of 0.50 and 4.6 respectively during the hottest period. For the complete monitoring period during the summer of 2008, the figures were 0.41 and 2.1. The lower figures were due to continuous pump operation inside the TDC even during periods of no cold production and a period when no cold was produced. However the internal pumps inside the TDC have been removed in the new version TDC to increase the electrical COP. System simulation and parametric studies will be employed to further determine how the electrical COP can be improved.     

Development and application of an updated whole-building coupled thermal,airflow and contaminant transport simulation program (TRNSYS/CONTAM)

The TRNSYS energy analysis tool has been capable of simulating whole-building coupled heat transfer and building airflow for about 10 years. The most recent implementation was based on two TRNSYS modules, Type 56 and Type 97. Type 97 is based on a subset of the airflow calculation capabilities of the CONTAM multizone airflow and contaminant transport program developed by the National Institute of Standards and Technology. This paper describes the development of new CONTAM capabilities in support of an updated combined, multizone building heat transfer, airflow and contaminant transport simulation approach using TRNSYS. It presents an illustrative case that highlights the new coupling capability and also presents the application of this coupled simulation approach to a practical design problem of the energy use related to airflow through entry doors in non-residential buildings.     

Simulation and experimental investigation of solar absorption cooling system in Reunion Island

With the development of technologies and the fast increase of our population we will need to adjust the conventional electrical source to meet the continuous increasing demand. Since the energy cost as well as the environmental awareness is growing fast, technologies using renewable energies appear as an interesting alternative. The aim of this research is to present a solar-driven 30 kW LiBr/H₂O single-effect absorption cooling system which has been designed and installed at Institut Universitaire Technologique of Saint Pierre. The first part of this article deals with the simulation of the solar thermal plant. A pilot plant has been setup as part of RAFSOL which is a research program managed by the national research agency (ANR).     

Finite element modeling of borehole heat exchanger systems: Part 2. Numerical simulation

Single borehole heat exchanger (BHE) and arrays of BHE are modeled by using the finite element method. Applying BHE in regional discretizations optimal conditions of mesh spacing around singular BHE nodes are derived. Optimal meshes have shown superior to such discretizations which are either too fine or too coarse. The numerical methods are benchmarked against analytical and numerical reference solutions. Practical application to a borehole thermal energy store (BTES) consisting of 80 BHE is given for the real-site BTES Crailsheim, Germany. The simulations are controlled by the specifically developed FEFLOW-TRNSYS coupling module. Scenarios indicate the effect of the groundwater flow regime on efficiency and reliability of the subsurface heat storage system.