生态沼气池探讨

1　发展农村沼气存在的问题农村推广沼气一直是以解决炊事用能为主要目的,普遍采用6～8ｍ3的水压式沼气池,这种以解决一日三餐的炊事用能为主要目的的“能源沼气池”有很大的局限性,主要表现在:11　对大多数农户来说,要靠沼气解决全部的炊事用能是困难的,它受到发酵原料严重短缺的制约发酵原料是生产沼气的物质基础。从理论上讲,农村沼气资源十分丰富,但问题在于:1.不是所有沼气资源都能开发利用,这里既存在经济效益问题,也存在技术问题(例如以秸秆做沼气发酵原料就存在这些问题);2.从总体上讲农村的沼气资源可能是丰富的,但具体到每个农户…     

沼气燃烧器的余热利用

沼气是一种优质气体燃料,主要成份是甲烷。农村沼气一般甲烷含量在60％左右。性能较好的沼气灶,热效率可达60％左右;沼气灯,一般相当于40—60瓦电灯光亮度,经济效益显著。用沼气作炊事和点灯用时,余热的损失至少在40％以上。我们对沼气灶具的余热利用进行了试烧比较,     

我国沼气综合利用模式及发展前景

沼气综合利用系指科学地把沼气、沼渣、沼液应用于生活、生产领域,充分发挥其经济效益、生态效益和社会效益的系列化实用技术。人们建造沼气池的主要目的是为了获得生活用能,满足炊事和照明的要求。随着商品化经济的发展和沼气技术的进步,沼气及其发酵残留物(沼渣、沼水)的应用面逐渐拓宽,陆续出现了一些沼气综合利用的实例,并在生产实践中不断改进、完善、扩展,形成沼气综合利用模式,因各地环境条件、物质基础、应用目的、经营方式、经营规模等方面的不同,导     

沼气肥养鱼一举两得

浙江省嘉善县农村能源办公室进行了用沼气肥养鱼的试验。试验用鸭粪投入沼气池发酵产气,用于照明和炊事用气,沼气肥自动流入鱼塘用于养鱼,这样做一方面节约了照明用电,消除了因夜间停电鸭棚无灯光鸭惊影响产蛋的不良因素;另一方面用沼气肥养鱼可提高产量降低成本。     

小型沼气-柴油双燃料发电技术探讨

沼气是一种具有较高热值的可燃气体，与其它燃气相比，其抗爆性能较好。传统上沼气多用于取暖、炊事和照明，随着沼气产量的不断增加，如何更高效地利用沼气，成为摆在我们面前的一项课题。沼气发电是随着沼气综合利用的不断发展而出现的一项新型沼气利用技术，是有效利用沼气的一种重要方式。     

海岛独立能源发电站可视化监控系统的实现

建立海岛独立能源发电站是解决海岛能源短缺问题和促进海岛经济发展的措施.文章利用发电站的发电装置控制系统的DSP作为下位机,通过RS485进行数据传输,用VB设计了可视化监控界面,建立了上位机的监控系统,为发电站的高效、稳定运行提供了有力的保障.     

万山海岛地区太阳能资源变化特征分析及评估

利用线性回归分析法、距平分析法、5年滑动平均法和Mann-Kendall检验法对万山海岛地区太阳总辐射量和日照时数进行分析,结果表明:万山海岛地区太阳总辐射量呈现略微上升趋势,月太阳总辐射量呈现单峰型分布,7月最高,2月最低;年日照时数呈现微弱的下降趋势,月日照时数呈双峰型分布,7月最高,3月最低。对万山海岛地区太阳能资源的分析和评估结果表明:万山海岛地区太阳总辐射量年平均值为4 996.25 MJ/m~2,属于资源丰富地区;太阳能资源稳定程度指标为3.7,属于资源较稳定地区。     

基于太阳能和生物质能的半干旱地区农村生态住宅设计

针对我国半干旱地区太阳能资源丰富和农村生活用能紧缺的特点,基于生态学、环境学和建筑学等方法原理,集被动式太阳房、太阳能热水器、太阳暖圈一沼气池、高效预制组装架空炕连灶等多项技术为一体,提出了基于太阳能和生物质能综合利用的半干旱地区农村生态住宅设计理念,并对生态住宅的热量供需平衡进行分析。结果表明：此类基于太阳能和生物质能综合利用的农村生态住宅模式,年可提供热量68070．24MJ,完全可满足半干旱地区农户日常生活中炊事、采暖、热水、照明以及家电使用等各种能耗需求。     

英达沼气供应站简介

在沈阳市东陵区英达村,已建成我省第一个按城市煤气化标准供气的沼气供应站,为该村酒厂发电和400户村民炊事常年供气。英达村酒厂日产白酒1.5吨,酒糟8吨,糟中含有粮食(玉米面)8％。为有效利用酒糟制取沼气,83年6月开始建沼     

沼气加快延庆新农村建设步伐

沼气,一直被视为农村的一种理想能源,是利用秸秆、人畜粪便等农村的主要污染源产生的一种清洁能源.在社会主义新农村建设中,沼气承载着更加重大的使命,它不但将为几亿农民提供生活用能,而且可以改善农村的环境,提高农村资源的综合利用效率,增加农民收入.     

Study of an indian biogas plant with a water pond

To overcome the problem of reduced biogas production, due to low ambient temperatures during the winter months of northern India, a novel concept of a shallow solar pond (SSP) water heater has been put forward and studied theoretically. The pond is proposed to be integrated with the dome of the conventional Indian (KVIC) biogas design. The results of the study show that system is capable of providing hot water upto a temperature of 40°C which, in turn, can be used for hot charging of the slurry besides reducing the heat losses from slurry to the ambient. Simultaneously, it helps in enhancing the slurry temperature from 20°C to 27°C.     

The self-sufficient solar house in Freiburg

The Fraunhofer Institute for Solar Energy Systems has built a completely self-sufficient solar house (SSSH) in Freiburg, Germany. The entire energy demand for heating, domestic hot water, electricity, and cooking is supplied by the sun. The combination of highly efficient solar systems with conventional means to save energy is the key to the successful operation of the house. Seasonal energy storage is accomplished by electrolysis of water and pressurized storage of hydrogen and oxygen. The energy for electricity and hydrogen generation is supplied by solar cells. Hydrogen can be reconverted to electricity with a fuel cell or used for cooking. It also serves as a back-up for low temperature heat. There are provisions for short term storage of electricity and optimal routing of energy. The SSSH is occupied by a family. An intensive measurement program is being carried out. The data are used for the validation of the dynamic simulation calculations, which formed the basis for planning the SSSH.     

Study on shallow solar pond applications at Tehran

In this study, a theoretical model which is validated experimentally is used to predict the performance of a shallow solar pond in Tehran. The theoretical and experimental results show good agreement. The maximum hourly water temperature of the shallow solar pond is found to lag behind the maximum hourly ambient temperature and solar radiation by 1–2 and 3.5 h, respectively.The maximum monthly daily-average water temperature follows the trend of the monthly daily-average solar radiation but leads the monthly daily-average ambient temperature in one month. The shallow solar pond, with 10-cm water depth, cannot be used as a thermal source in winter but can be used for many thermal applications in summer. With 5-cm water depth, the shallow solar pond can be used as a thermal source for low heat applications in most of the winter but can be used, even for moderate applications, where high temperature up to 95°C is obtained in summer. Using a reflector makes the 10-cm depth shallow solar pond useful for low heat applications and the 5-cm depth useful for moderate heat applications in most of the winter. Using a double cover top glazing is found to have no effect on improving the system performance.     

Field testing on nonsalt solar ponds

A new type of nonsalt solar pond was investigated by field testing. The roof of the solar pond was formed using a transparent double film. Three kinds of tests were carried out under the following conditions: (1) insulating pellets were packed between the layers of the transparent double film of the roof at sunset; (2) the water surface of the pond was insulated using only the two transparent films; (3) the water surface of the pond was covered by the double film with the top surface blackened on which solar energy can be collected, while pond water was circulated using a solar cell powered submerged water pump. The warm water stored in the solar pond by the above methods was utilized as a heat source for a gas engine powered heat pump used to heat a greenhouse. In this report, the results of the field tests on the above solar ponds and greenhouse heating system are discussed. Also the utility of a combination plant using a solar pond and underground borehole storage system is evaluated.Important conclusions on performance are as follows: (1) collection efficiencies of these solar ponds become 9–54% corresponding to the weather conditions and pond temperatures; (2) maximum temperature of the pond water under weather conditions at Osaka is about 80°C; (3) the solar pond can be effectively utilized for heating a greenhouse; (4) the combination plant using the solar pond and the underground storage layer can store heat of 1119 MJ m⁻² yr⁻¹.     

Conclusions from the Representative of the European Parliament

This article describes a co-generation plant based on the biogas being produced from the waste of distillery plant and highlights the possible configuration in which the plant can be hybridized with auxiliary solar energy source having the advantage of using financial incentives in several countries. In hybridization, the solar heat is used for heating the boiler feed water. The solar heat-generating unit consists of line focus parabolic trough collector, heat transportation system and heat delivery unit such as heat exchanger. The simulation model of heat and mass transfer processes in the solar field as well as the balance of the system is developed to investigate the technological feasibility of the concept in terms of plant yield and matching of subsystems.     

联合太阳能沼气的冷热电供能系统的集成及经济性分析

冷热电联供是一种先进、高效的能源系统,目前在我国应用的主要问题是天然气成本高,导致系统经济性差。太阳能和沼气是非常清洁的可再生能源,在我国来源广泛且廉价。将冷热电联供系统与太阳能、沼气完美地结合起来,集成为联合太阳能沼气的冷热电供能系统。该系统较为合理的组合方式是采用太阳能沼气池作为燃料提供装置,采用微型燃气轮机、余热锅炉、溴化锂吸收式制冷机、蒸汽换热器等作为供电、供冷和供热机组,采用太阳能集热器、换热器等装置为沼气池加热,太阳能不足时采用尾气加热。该系统能够实现能量的梯级利用,提高一次能源利用率,达到综合用能的目的,同时可有效治理环境。以某酒店作为该系统的用户对象,分析其经济性并与常规模式进行对比。结果表明,该系统一次能源利用率为74.8%,而常规模式为62.3%;综合能源价格为0.3398元/(k W·h),而现阶段电网电价约为0.6元/(k W·h);环境与减排评价指标也具有明显优势。     

Heat loss reduction from the gas holder/fixed gas dome of a community-size biogas plant

The decrease in the yield of biogas in winter months in the usual systems—fixed dome and floating dome types—can be checked by providing insulation on the inner surface of the gas holder. A mathematical model has been developed to study the effect of putting in such insulation. A novel concept of making a shallow solar pond water heater over the gas holder to reduce the heat losses and simultaneously provide water for hot charging is proposed and analysed. Calculations corresponding to a typical winter day at New Delhi have been made for a numerical appreciation of the developed analysis.     

Solar pond with honeycomb surface insulation system

A solar pond consisting of transparent compound honeycomb encapsulated with Teflon film and glass plates at the bottom and top surface respectively, floating on the body of a hot water reservoir is considered and analysed for the heat transfer processes in the system. A mathematical model is developed where the energy balance equation of the convective water is formulated by considering its capacity effects, various heat losses and solar energy gain through the surface insulation and is solved by the finite difference method. Transient rate of heat collection and storage characteristics are investigated. Explicit emphasis is laid on the effect of the thickness of the bottom encapsulation on the year-round thermal performance of the system and results seem to favour the minimum thickness. The annual average efficiency of the transparent honeycomb insulated solar pond is found to be higher than the conventional salt gradient pond by a factor of about 2.     

Saturated solar ponds: 1. Simulation procedure

The mass and energy balances on the upper convective zone, nonconvective zone, and lower convective zone of a saturated solar pond are written to yield a set of nonlinear partial differential equations. These are solved numerically to predict the thermal performance of the pond over a long period of time for various initial and boundary conditions. This model considers external parameters such as hourly variation of incident solar radiation, ambient temperature, air velocity, and relative humidity. Temperature and concentration dependence of density, thermal conductivity, specific heat, and mass diffusivity are taken into account. Heat transfer modes considered between the upper convective zone and the ambient are convection, evaporation, and radiation. Ground heat losses from the lower convective zone are also considered. This model is used to study the development of temperature and concentration profiles inside a saturated solar pond. This model can also be used to predict the long-term performance of a saturated solar pond for various heat extraction temperatures and rates.     

Performance assessment of a magnesium chloride saturated solar pond

This paper deals with the experimental investigation of a magnesium chloride saturated solar pond and its performance evaluation through energy and exergy efficiencies. The solar pond system is filled with magnesium chloride containing water to form layers with varying densities. A solar pond generally consists of three zones, and the densities of these zones increase from the top convective zone to the bottom storage zone. The incoming solar radiation is absorbed by salty water (with magnesium chloride) which eventually increases the temperature of the storage zone. The high-temperature salty water at the bottom of the solar pond remains much denser than the salty water in the upper layers. Thus, the convective heat losses are prevented by gradient layers. The experimental temperature changes of the solar pond are measured by using thermocouples from August to November. The densities of the layers are also measured and analysed by taking samples from at the same point of the temperature sensors. The energy and exergy content distributions are determined for the heat storage zone and the non-convective zone. The maximum exergy destructions and losses appear to be 79.05 MJ for the heat storage zone and 175.01 MJ for the non-convective zone in August. The energy and exergy efficiencies of the solar pond are defined as a function of solar radiation and temperatures. As a result, the maximum energy and exergy efficiencies are found to be 27.41% and 26.04% for the heat storage zone, 19.71% and 17.45% for the non-convective zone in August, respectively.