小型太阳能复合供热系统的应用与设计

结合欧洲太阳能应用的经验及国内的实际情况,介绍了小型太阳能复合供热系统(包括生活热水和供暖)常用形式的流程和特点。介绍了集热器、蓄热水箱、辅助热源的设计。     

Achieving total domestic hot water production with renewable energy

Various means of producing domestic hot water (DHW) with renewable energy in zero net energy homes (ZNEH) are examined for two climates (Montréal and Los Angeles). Four alternatives are examined: (i) a regular electric hot water tank; (ii) the desuperheater of a ground-source heat pump (GSHP) with electric backup; (iii) thermal solar collectors with electric backup; and (iv) a heat pump water heater (HPWH) indirectly coupled to a space conditioning GSHP. Results show that heating DHW with thermal solar collectors with an electric backup (which is either provided by the photovoltaic (PV) panels or the grid in a ZNEH) is the best solution for a ZNEH. The second part of this paper focuses on determining what should be the respective areas of the thermal solar collectors and PV array to obtain the least expensive solution to achieve total DHW production with renewable energy.     

Long term operation of a solar assisted ground coupled heat pump system for space heating and domestic hot water

This paper introduces a solar-assisted ground-coupled heat pump (SAGCHP) system with heat storage for space heating and domestic hot water (DHW) supply. The simulation results of the system's detailed operating performance are presented. The optimization of the system design is carried out by the TRNSYS and a numerical simulation is performed for continuous operation of 20 years under the meteorological conditions of Beijing. Different control strategies are considered and the operational characteristics of each working mode are studied. The simulating results show that the long term yearly average space heating efficiency is improved by 26.3% compared to a traditional ground coupled heat pump (GCHP) system because the solar thermal collecting system is used to elevate the thermal energy in the soil and to provide direct space heating with heat storage. At the same time, the underground heat load imbalance problem for a heating load dominated GCHP is solved by soil recharging during non-heating periods, while extra solar energy is utilized to supply DHW. The flexibility and high efficiency of the SAGCHP system could offer an alternative for space heating and DHW supply by heat pump technology and solar energy in cold winters of northern China.     

A solar heating system with annual storage

A heating system is described for a one-family house in Trento, Italy, using solar collectors with buried long-term storage water tanks, made of reinforced concrete and internally water-proofed, assisted by an electrical water—water type heat pump.

The following design parameters are described and evaluated:

a. the annual energy requirement for the house;

b. the solar energy available;

c. the average monthly efficiency of the collectors;

d. the storage tank—ground heat flows, taking storage insulation, water storage temperature and COP to be variable with time;

e. the overall energy balance of the system for the house in question.

The conclusion is that the proposed system can cover the annual energy required for this house with an electrical consumption equal to 20% of the total.     

Development and experimental validation of a novel indirect-expansion solar-assisted multifunctional heat pump

This paper proposes a novel indirect-expansion solar-assisted multifunctional heat pump (IX-SAMHP) which integrates a domestic heat pump with a solar water heater. The IX-SAMHP can not only work in operation modes included in the two household appliances, but also operate in four new energy-saving operation modes for the space cooling, space heating and water heating. All operation modes have functioned successfully and can be switched to each other smoothly on a purpose-built experimental setup. Experiments of the heat pump water heating mode at outdoor air temperatures of 8 °C and 15 °C and the solar-assisted space heating mode at indoor air temperatures of 20 °C have been investigated in detail. Electric heaters were used to simulate solar radiation intensity in different weather conditions. The experimental results show that the IX-SAMHP can produce hot water with much less electric consumption in cloudy days compared with a solar water heater and can operate in much higher coefficient of performance than a domestic heat pump in cold winter. The IX-SAMHP is especially suitable for the regions abundant in solar radiation where the space heating, space cooling and water heating are required all the year round.     

银川地区被动式太阳房的室温预测

被动式太阳房是一种经济有效地利用太阳能采暖的建筑,银川地区太阳能热水器已经得到了广泛的应用,但被动式太阳房的应用较少。本文对银川地区直接受益窗与集热蓄热墙的组合式太阳房的室内温度进行预测,分析其热舒适性,以便今后更近一步的研究。     

Experimental study of a ground-coupled heat pump combined with thermal solar collectors

This paper presents the experimental study of a ground-coupled heat pump used in a 180 m² private residence and combined with thermal solar collectors. This process, called GEOSOL, meets domestic hot water and heating–cooling building energy needs. Solar heat is used as a priority for domestic hot water heating and when the preset water temperature is reached, excess solar energy is injected into the ground via boreholes. This system has the advantage to contribute to the balance of the ground loads, increasing the operating time of the solar collectors and preventing overheating problems. After 11 months in operation, the power extracted and injected into the ground had average values of 40.3 and 39.5 W/m, respectively. Energy injected into the ground represents 34% of the heat extracted, and the heat pump's coefficient of performance (COP) in heating mode had an average value of 3.75. In addition, the domestic hot water solar fraction had an average value higher than 60% for the first 11 months in operation.     

Exergetic modeling and assessment of solar assisted domestic hot water tank integrated ground-source heat pump systems for residences

The present study deals with the exergetic modeling and performance evaluation of solar assisted domestic hot water tank integrated ground-source heat pump (GSHP) systems for residences for the first time to the best of the author's knowledge. The model is applied to a system, which mainly consists of (i) a water-to-water heat pump unit (ii) a ground heat exchanger system having two U-boreholes with an individual depth of 90 m, (iii) a solar collector system composing of rooftop thermal solar collectors with a total surface area of 12 m², (iv) a domestic hot water tank with a electrical supplementary heater, and (v) a floor heating system with a surface of 154 m², and (vi) circulating pumps. Exergy relations for each component of the system and the whole system are derived for performance assessment purposes, while the experimental and assumed values are utilized in the analysis. Exergy efficiency values on a product/fuel basis are found to be 72.33% for the GSHP unit, 14.53% for the solar domestic hot water system and 44.06% for the whole system at dead (reference) state values for 19 °C and 101.325 kPa. Exergetic COP values are obtained to be 0.245 and 0.201 for the GSHP unit and the whole system, respectively. The greatest irreversibility (exergy destruction) on the GSHP unit basis occurs in the condenser, followed by the compressor, expansion valve and evaporator.     

Field performance of a Japanese low energy home relying on renewable energy

This paper describes the construction and evaluation of an experimental low energy home assisted by a hybrid system using natural energy resources and unused energy. The home, for which a ground source heat pump (GSHP) system has been installed, was built on the campus of Hokkaido University, Japan in March 1997. The total floor area of the home is 192 m². This home is super insulated and airtight; the calculated coefficient of heat loss is 0.97 W/m² K. It has various passive strategies including direct solar heat gain and a ventilation system with an exhaust stack. Photovoltaic (PV) modules, wind power and solar collectors are adopted in order to achieve self-sufficiency in electric power and domestic hot water (DHW) supply. A GSHP is used for space heating and cooling. Two vertical steel wells are used as vertical earth heat exchangers (VHE). In summer, there is a floor cooling system using piped cold water from the VHE.Approximately 80% of the home’s total energy was provided by PV modules, solar collectors, as well as underground and exhaust heat. The annual amount of purchased energy during the test period was 12.5% that of a typical home in Hokkaido.     

Experimental investigation and theoretical analysis of solar heating and humidification system with desiccant rotor

In this paper, a solar heating system, which combines the technologies of evacuated tube solar air collector and rotary desiccant humidification together, has been configured, tested and modeled. The system mainly includes 15 m² solar air collectors and a desiccant air-conditioning unit. Two operation modes are designed, namely, direct solar heating mode and solar heating with desiccant humidification mode. Performance model of the system has been created in TRNSYS. The objective of this paper is to check the applicability of solar heating and evaluate the feasibility and potential of desiccant humidification for improving indoor thermal comfort. Experimental results show that the solar heating system can convert about 50% of the received solar radiation for space heating on a sunny day in winter and increases indoor temperature by about 10 °C. Compared with direct solar heating mode, solar heating with desiccant humidification can increase the fraction of the time within comfort region from about 10% to 20% for standalone solar heating and from about 30% to 60% for solar heating with auxiliary heater according to seasonal analysis. It is confirmed that solar heating with desiccant humidification is promising and worthwhile being applied to improving indoor thermal comfort in heating season.     

Housing at Clonmel,Ireland

A 63‐house public authority scheme was chosen to monitor the energy performance of three house types: ‘standard’, ‘well insulated’ and ‘passive solar’, all essentially based on a prize‐winning house design in an EEC competition. However, inadequate space heating — since replaced —vitiated many of the expected energy savings, and in the passive solar design heat losses from the uninsulated south‐facing conservatory largely offset the solar gains. Experience also showed that some form of curtaining should be assumed when considering direct solar gain through windows. The author is a Senior Research Officer at An Foras Forbartha.     

集成太阳能热水器窗系统技术浅谈

建筑能耗在我国所有能耗中占的比重较大。其中生活热水是排在供暖、空调和照明之后的第四大建筑能耗[1]。充分利用太阳能与建筑结合的技术,将太阳能作为生活热水的能量来源,是降低建筑能耗行之有效的方式。新型太阳能热水器窗系统在传统门窗和太阳能热水器系统功能的基础上,将太阳能真空管与窗的中空玻璃相结合,使得窗具有热水器的功能,进一步拓展了门窗系统的功能,降低了建筑能耗,提升了资源利用率;新型太阳能热水器窗系统结构紧凑,单位面积上对太阳能利用率较高。     

村镇住宅建设与太阳能利用

通过对我国太阳能资源分布情况的分析以及太阳能应用可行性研究,提出了一种既节约能源又节省投资的太阳能绿色建筑设计方案.将建筑设计技术与太阳能利用技术相结合,建造一种利用南外墙进行集热和蓄热的被动式太阳房或利用太阳能热水循环技术的主动式太阳房,解决严寒季节供暖问题以及生活热水供应问题,对发展村镇建设,提高人居环境质量,创建"和谐社会"有着重大的现实意义.     

Electrical savings by use of wood pellet stoves and solar heating systems in electrically heated single-family houses

This study investigates how electrically heated single-family houses can be converted to wood pellets- and solar heating using pellet stoves and solar heating systems. Four different system concepts are presented and system simulations in TRNSYS evaluate the thermal performance and the electrical savings possible for two different electrically heated single-family houses. Simulations show that the electricity savings using a wood pellet stove are greatly affected by the level of comfort, the house plan, the system choice and if the internal doors are open or closed. Installing a stove with a water-jacket connected to a radiator system and a hot water store has the advantage that heat can be transferred to domestic hot water and be distributed to other rooms. Such systems leads to that more electricity can be replaced, especially in houses having a traditional plan. Though it is unnecessary to have too many radiators connected to a stove with a low fraction of energy heating the water jacket. Today's most common control strategy for stoves (the on/off-control) results in unnecessarily high emissions. A more advanced control varying the heating rate from maximum to minimum to keep a constant room temperature reduces the number of starts and stops and thereby the emissions.     

The potential for solar space heating in Scotland

This paper investigates the relative effectiveness of passive-type solar-assisted space heating systems at various latitudes within the British Isles. A comparison is made of the useful solar gain of the same system linked to the same house at four different locations.

Month by month energy balances indicate that the annual useful solar contribution at the highest latitude (Lerwick, 60°N) is about 35% higher than at the lowest latitude (Kew, 53°N). The main reason for this difference is the higher heating loads in the North, particularly outside the winter months. The estimated available irradiation on south facing vertical surfaces was almost the same at all four locations. Previous work in the UK indicates that, contrary to the conclusions in this paper, more southerly latitudes were the most favourable for solar space heating. The reasons for the disparity are discussed. It is recommended that research and development of passive solar-assisted space heating systems should be most vigorously pursued in the more northerly latitudes of the British Isles, where both the potential benefit and the need are greatest.     

Energy-efficient terrace houses in Sweden: Simulations and measurements

Reducing energy use in buildings is essential to decrease the environmental impact. Outside Gothenburg in Sweden, 20 terrace houses were built according to the passive house standard and completed in 2001. The goal was to show that it is possible to build passive houses in a Scandinavian climate with very low energy use and to normal costs. The houses are the result of a project including research, design, construction, monitoring and evaluation. The passive house standard means that the space heating peak load should not exceed 10 W/m² living area in order to use supply air heating. This requires low transmission and ventilation losses and the building envelope is therefore highly insulated and very airtight. A mechanical ventilation system with approximately 80% heat recovery is used. The electric resistance heating in the supply air is 900 W per living unit. Solar collectors on the roof provide 40% of the energy needed for the domestic hot water. The monitored delivered energy demand is 68 kWh/m² a. Energy simulations show that main differences between predicted and monitored energy performance concern the household electricity and the space heating demand. Total delivered energy is approximately 40% compared with normal standard in Sweden.     

Economic and exergy analysis of alternative plants for a zero carbon building complex

The feasibility of zero carbon emission plants for heating, air conditioning and domestic hot water (DHW) supply, is analyzed, with respect to conventional plants, for a new residential building complex to be constructed, in Northern Italy. Two zero carbon plants are considered: the first is composed of air-to-water heat pumps for space heating and cooling, PV solar collectors, air dehumidifiers, thermal solar collectors and a wood pellet boiler for DHW supply; in the second, the air-to-water heat pumps are replaced by ground-coupled heat pumps. The conventional plant is composed of a condensing gas boiler, single-apartment air to air heat pumps, and thermal solar collectors. The economic analysis shows that both zero carbon plants are feasible, and that the air-to air heat pumps yield a shorter payback time. The exergy analysis confirms the feasibility of both plants, and shows that the ground coupled heat pumps yield a higher exergy saving.     

冷风渗透对太阳房热性能的影响研究

通过对青海某地太阳房的测试分析研究,确定了冷风渗透量对太阳房集热量和室温影响的计算方法。并知该太阳房的供暖效果和节能效果较好,但其集热墙的玻璃幕墙和房间门窗的密闭性较差,导致该玻璃幕墙和房间冷风渗透量较大,影响了集热墙的集热量及集热效率和太阳房的供暖与节能效果。因此在太阳房建设的设计与施工的各个环节中必须充分重视玻璃幕墙和房间门窗的密封性问题,以减少冷风渗透的能耗,提高太阳房的供暖效果和节能效率。     

加拿大卡尔加里市Okotoks小镇太阳能小区建设

简要介绍了北美目前最大的跨季太阳能储存项目——加拿大0kotoks小镇的太阳能小区建设，对其太阳能供热系统的工作原理及利用土壤床作为储能体进行大规模跨季节太阳能储存的方法进行了分析。该项目根据不同季节可利用太阳能数量的不同，分别设置了短期（临时）太阳能储箱（STTS）及跨季节太阳能储存箱（BTES），以提高太阳能的利用率。其中，BTES的效率可达50％以上。小区太阳能家用热水系统（DWH）可满足住户60％的热水需求，而太阳能采暖系统则可满足90％采暖要求；建成后每幢住宅每年可减排5t温室气体，整个小区可减排260t／年。     

多种生活热水供热系统技术及经济对比分析

以小区中央热水系统改造为背景,对太阳能集热器+电加热器热水系统、空气源热泵+电加热器热水系统、空气源热泵+板式换热器+电加热器热水系统、水源热泵、地源热泵热水系统等几种热源供热系统进行了对比分析,结果表明利用空气源热泵+板式换热器+电加热器热水系统最节能,与小区原电加热系统相比可以使热水工作费用降低76.8％.