农业温室供热系统的研究和设计

农业温室（以下简称温室）是具有必要设备的、能够常年为作物生长和发育提供所需条件的特殊建筑物。温室是一个特殊的生产车间,冬季要供热。结合示范工程温室的设计,着重介绍了温室的型式、覆盖材料、热负荷计算、供热系统形式以及节能运行方式等。     

Experimental analysis of model predictive control for an energy efficient building heating system

Low energy buildings have attracted lots of attention in recent years. Most of the research is focused on the building construction or alternative energy sources. In contrary, this paper presents a general methodology of minimizing energy consumption using current energy sources and minimal retrofitting, but instead making use of advanced control techniques. We focus on the analysis of energy savings that can be achieved in a building heating system by applying model predictive control (MPC) and using weather predictions. The basic formulation of MPC is described with emphasis on the building control application and tested in a two months experiment performed on a real building in Prague, Czech Republic.     

地板辐射采暖和风机盘管采暖室内热环境及能耗比较

对地板辐射和风机盘管两种采暖方式进行了实验研究和理论分析，提出了围护结构临界热阻临的概念，推导出了两个采暖系统的热舒适性随围护结构热阻和冷风渗透量波动的变化关系。实验验证了地板辐射采暖既改善了室内热环境又显示较好的节能效果。     

Review on solar air heating system with and without thermal energy storage system

In order to produce process heat for drying of agricultural, textile, marine products, heating of buildings and re-generating dehumidify agent, solar energy is one of the promising heat sources for meeting energy demand without putting adverse impact of environment. Hence it plays a key role for sustainable development. Solar energy is intermittent in nature and time dependent energy source. Owing to this nature, PCMs based thermal energy storage system can achieve the more popularity for solar energy based heating systems. The recent researches focused on the phase change materials (PCMs), as latent heat storage is more efficient than sensible heat storage. In this paper an attempt has been made to present holistic view of available solar air heater for different applications and their performance.     

地板辐射式供暖的能耗分析

依据辐射供热室内辐射与对流综合作用的传热规律,计算和分析了地板辐射式采暖房间能耗的构成及影响因素,给出在相同舒适度条件下,几种常见的围护结构地板辐射式供暖房间的能耗随地表面加热温度的变化关系,并与相应的对流式采暧进行了对比。     

燃气炉与太阳能联合供热系统的研究

阐述了燃气炉与太阳能联合供热系统的设计、制造和控制方法,在令人舒适满意的基础上确保经济性。     

供热系统中动力设备的节能问题分析

分析了供热系统中动力设备能耗偏高的原因,主要为低负荷率运行和阀门调节造成的节流损失;比较了不同流量调节方法的特点;指出应通过动力设备容量的合理配置配合合适的调速方法以保证动力设备高效运行;分析了不同设备的合理调节范围;并利用具体方案比较分析了变频调节的节能幅度。     

Mode selection of China's urban heating and its potential for reducing energy consumption and CO2 emission

China's carbon dioxide (CO₂) emission ranks the highest in the world. CO₂ emission from urban central heating, which has an average annual growth rate of 10.3%, is responsible for 4.4% of China's total CO₂ emission. The current policy for improving urban central heating focuses on replacing coal with natural gas. This paper analyzes the existing situation and problems pertaining to urban heating, and evaluates the potential for reducing energy consumption and CO₂ emission by heat pump heating. The results show that the current policy of replacing coal with natural gas for urban central heating decreases energy consumption and CO₂ emission by 16.6% and 63.5%, respectively. On the other hand, replacing coal-based urban central heating with heat pump heating is capable of decreasing energy consumption and CO₂ emission by 57.6% and 81.4%, respectively. Replacing both urban central and decentralized heating with heat pump heating can lead to 67.7% and 85.8% reduction in energy consumption and CO₂ emission, respectively. The decreases in CO₂ emission will account for 24.5% of China's target to reduce total CO₂ emission by 2020.     

Meeting the electricity demand for the heating of greenhouses with hydrogen: Solar photovoltaic-hydrogen-heat pump system application in Turkey

Providing the heating system with coal in greenhouses causes harmful results in terms of carbon emissions. In this study, analyzes were performed to meet the electrical energy required for the heating system with a heat pump from a solar photovoltaic-hydrogen system. For floor area 25000 m² where greenhouses the required energy is obtained directly from hydrogen without using a heat pump 3000 m² solar panel area required. The use of a heat pump reduces energy needs but it is also not feasible for large greenhouses. For convenience, a solar photovoltaic-hydrogen-heat pump system analysis was also made for 1000 m² floor area greenhouses and it is found that the 24 m² solar panel area is adequate in terms of meeting energy demand. Using a solar-hydrogen-heat pump system reduces carbon emissions by 86.5 tons per 1000 m² floor area greenhouse. Considering the hydrogen storage system becomes unfeasible. We normalized the greenhouse floor area to 1 m² and proposed reference values for hydrogen to be produced in 1 h, storage, and PV area. In addition, an analysis was made for the use of hydrogen energy for greenhouses that do not require a heating system and only work with a water pump.     

Combining a new baseboard radiator with a fan coil system for improving heating performance and reduce energy consumption

In the present work, the heating performance of a new system combined with a new modified baseboard radiator and fan coil is investigated. Using longitudinal fins with special geometry and also forced airflow at the end of the system causes that at the lower inlet water temperature compared with the conventional models, higher heat output rate be obtained. The heat output rate of the new modified system is obtained by experimental metrology based on the European Standard No. EN-442. Temperature and velocity distribution in the room space is done by simulation of the modified system in the Flovent software. Computational fluid dynamics (CFD) results are validated against experimental results and there is a good agreement between them. Also, the energy consumption of the system during the winter season is calculated in TRANSYS software. Experimental results show that the heat output rate of a new modified heating system with inlet water temperature in the range of 45–55°C is on average 4.17 times higher compared with the conventional model. CFD simulation also showed that the combined system provides good thermal comfort conditions. Energy consumption of the new system reduced about 13% compared with conventional models.     

轧钢加热炉能耗分析

本文分析了我国轧钢加热炉的能耗状况,指出了我国轧钢加热炉中存在的问题,着重阐述了我国轧钢加热炉的节能措施。这些措施主要有:采用先进工艺;对加热炉进行技术改造和采用节能型加热炉;加强节能管理等。     

太阳能热水系统结合地板采暖在高层住宅中的应用

介绍太阳能热水系统结合低温热水地板采暖系统的工作原理,以上海地区为例,在高层住宅中应用壁挂式太阳能集热器,可以实现太阳能与建筑一体化。对该太阳能系统进行节能效益分析,结果表明,系统的动态回收期为3.98年。     

Impact of climate change on building heating energy consumption in Tianjin

This paper investigated the variation of building heating energy consumption caused by global warming in Tianjin, China. Based on the hourly historical and monthly projected future (B1/A1B emissions scenarios) meteorological data, the variation of those relevant meteorological parameters was first analyzed. A TRNSYS simulation model for a reference building was introduced to investigate historical variation of office building energy consumption. The results showed that the 10-year-average heating energy consumption of 2001–2010 had reduced by 16.1% compared to that of 1961–1970. By conducting principal component analysis and regression analysis, future variation of building heating load was studied. For B1/A1B emissions scenarios, the multi-year-average heating load was found to decrease by 9.7% (18.1%)/10.2% (22.7%) compared to that of 1971–2010 by 2011–2050 (2051–2100).     

Experimental study of the burning-cave hot water soil heating system in solar greenhouse

In the northern China areas, the traditional heating methods are widely used in solar greenhouse, for example: electric heating, hot air heating, hot water heating, burning-cave heating etc. If copying the assuring building indoor environment of constant heating ways into solar greenhouse, it will further increase building energy consumption, thus improving the efficiency of energy utilization, establishing appropriate growing environment, and realizing the agricultural waste recycling are important ways of consistent with the Chinese conditions, construction of sustainable development, improving the efficiency of the greenhouse production. To solve the problem of traditional heating method for high heating energy consumption, the inharmonious between greenhouse air temperature and soil temperature, uneven soil temperature, the research build the burning cave hot water soil heating system of solar greenhouse experimental platform in accordance with principle of energy cascade utilization. This experiment platform will transfer burning cave internal heat into soil heating system. The soil is evenly heated by system. Through testing the actual operation effect of the burning cave hot water soil heating system of new solar greenhouse, electric heating system, no taking any heating measures system, burning cave hot water soil heating system of solar greenhouse can improve the soil average temperature 5 ∼ 6 °C. This research provides experimental basis for practical applications and promotion.     

Experimental determination of the overall heat loss coefficient for energy requirement of greenhouse heating

This paper presents an experimental determination of energy requirement for greenhouse heating. The overall heat loss coefficient, heat input, the control factor for air‐tightness, the rate of heat loss and the thermal screen effectiveness were calculated. The relationships between the overall heat loss coefficient and the wind speed, and the outside temperature were modelled, including the measured and calculated values. It was found that the thermal screen effectiveness was 16 and 19.8% for the polyethylene (PE) and polyester screens, respectively. Copyright © 2005 John Wiley & Sons, Ltd.     

The demand function for residential heat through district heating system and its consumption benefits in Korea

The demand for residential heat (RH) through a district heating system (DHS) has been and will be expanded in Korea due to its better performance in energy efficiency and the abatement of greenhouse gas emissions than decentralized boilers. The purposes of this paper are two-fold. The first is to obtain the demand function for DHS-based RH in Korea and investigate the price and income elasticities of the demand employing the quarterly data covering the period 1988–2013. The short-run price and income elasticities are estimated as −0.700 and 0.918, respectively. Moreover, the long-run elasticities are −1.253 and 1.642, respectively. The second purpose is to measure the consumption benefits of DHS-based-RH employing the economic theory that they are the sum of the actual payment and consumer surplus for the consumption. Considering that the average price and estimated consumer surplus of the DHS-based RH use in 2013 are computed to be KRW 87,870 (USD 84.1) and KRW 62,764 (USD 60.1) per Gcal, the consumption benefits of the DHS-based RH are calculated to be KRW 150,634 (USD 144.2) per Gcal. This information can be beneficially utilized to conduct an economic feasibility study for a new DHS project related to RH supply.     

Energy flow through the flat-plate solar water heating system

A simulation model of the flat-plate solar water heating system is used to trace the flow of energy through the system from the collector to storage and load for a system operating under idealised sunlight conditions.     

间接连接区域热水供暖系统特性及控制策略仿真

应用质量和能量守恒定律,创建间接连接热水区域供暖系统动态模型。通过仿真,分析系统补水率、散热器及换热器面积、室外温度、太阳辐射、室内得热、散热器循环流量和供水温度对系统和用户运行的影响。根据燃料控制器及温度控制器不同配置,仿真及分析了6种控制策略运行和能耗情况。控制仿真显示,基于用户侧的控制策略可实现系统节能及用户热舒适性双赢目标。     

Modeling heat transfer and air circulation by convection in bottom-heated agricultural greenhouses

In agricultural greenhouses, effective heating systems are essential for maintaining proper temperature control and air circulation during the winter. This study delves into the analysis of heat exchange through natural convection within heated greenhouses, with a particular emphasis on the impact of bottom heating. Two distinct types: mono-chapel and bi-chapel, each featuring triangular or spherical roofs are examined. To capture the variable roof shapes, we employ a change-of-variable method, and the numerical solutions are obtained using the finite volume method. The results show that heat transfer is enhanced by increasing the Rayleigh number. This improvement differs according to the shape of the roof. Heat transfer decreases by about 5% for the spherical mono-chapel case compared to the triangular case for Ra = 10³. For Ra = 10⁵, the monospherical case favors heat transfer, with an increase of 0.35% compared to the triangular case. In the case of bi-chapel roof, heat transfer is greater with a triangular roof for Ra = 10³, showing an increase of 6.4% compared to the spherical case. This study not only sheds light on the fundamental aspects of heat transfer in greenhouses but also provides valuable insights for optimizing greenhouse design based on specific roof configurations and heating conditions.     

Fuzzy controlled central heating system

In this paper a comparison study was carried out in order to understand how two different systems, classical and fuzzy logic control of central heating affect the economy and comfort of private homes or offices. Also a literature review was done to help decide which one of these systems is more effective. The objective of the fuzzy controller heating system is to estimate the actual heat requirement of the house. It uses a total of five inputs, four of which are derived from energy consumption curve, using conventional digital filtering techniques; the fifth is the average outdoor temperature, whereas, the classical control system burns diesel type fuel in its furnace to heat the water supply (boiler). From the boiler, the hot water is distributed by a pipe system to the individual radiators in the house. Thereby, it is shown that the fuzzy controlled heating system is more effective, also it maximizes the economy and the comfort of the consumer. Copyright © 2002 John Wiley & Sons, Ltd.