Selection of micro turbines to meet electrical and thermal energy needs of residential buildings in Iran

Micro gas turbines are considered to meet the electrical, domestic hot water, heating and cooling energy needs of a residential building located in Tehran, Ahvaz and Hamedan. The building is 10 stories high and has a total of 8000 m² floor area with the peak demands of electricity of 32.96 kW, DHW of 0.926 kW, heating load of 1590 kW and the cooling load of 2028 kW, when the building is located in Tehran. With these demands, 30 micro turbines of 30 kW (nominal power) are needed to meet all the energy needs of the building. The excess electricity generated by the micro turbines is to be used in a heat pump, and the energy in the exhaust gases is to be used to meet other thermal energy needs of the building. With proper energy conservation measures and the use of ceiling fans in each room, the peak heating and cooling demands of the building were reduced to 225 kW and 760 kW, respectively. With these measures, two micro gas turbines of 30 kW nominal capacity, or one of 40 kW, could meet all the electrical, DHW, heating and a great portion of the cooling needs of the building. The remaining cooling needs of the building during the hot hours of summer could be met by an additional absorption refrigeration, utilizing natural gas as its energy source. It is recommended that with energy conservation measures, the heating and cooling loads of buildings be reduced as much as possible, and micro gas turbines be employed to meet the electrical demands and a portion of heating and cooling needs. The remaining thermal energy needs are to be met through the use of natural gas. Only with these measures, the on-site combined heat and power (OS-CHP) is a viable option for residential buildings in Iran.     

Potential use of cold thermal energy storage systems for better efficiency and cost effectiveness

The present article deals with the employment of combined heat and power (CHP) micro gas turbines using natural gas and cold thermal energy storage system (CTES) in Tehran (with mild climate), Bandarabas (with hot and humid climate) and Kerman (with semi-hot climate). A micro CHP produces electricity to meet the electrical energy needs of the building, and it is also considered to meet part of the heating, cooling and domestic hot water energy needs through a heat pump and refrigeration system. A detailed study considering the effect of CTES system on the selection of micro gas turbines of a residential building located in Tehran is performed. The results show that since the number of micro gas turbines is dependent on the maximum cooling load required in the summer using CTES system reduces the CHP micro gas turbine units from 21 to 11 and costs from US$ 1,133,221 to US$ 799,061 (29.5% economical) for the residential building which is located in Tehran. Also, using this system in Kerman and Bandarabas reduces the micro CHP gas turbine units from 21.75 to 11.40, respectively.     

Modeling and economic analysis of gas engine heat pumps for residential and commercial buildings in various climate regions of Iran

There is an increasing trend in using heat pumps in air conditioning (heating/cooling) systems of residential and commercial buildings. The required power to drive the compressor of vapor compression heat pump cycles may be provided by either an electrical motor or an internal combustion engine. In this paper thermal modeling and economic analysis of gas engine heat pumps (GEHPs) are presented based on energy and mass balance equations as well as the gas engine operating parameters (such as thermal efficiency, fuel consumption and fuel mass flow rate) and heat pump operating parameters (such as evaporator and condenser capacity and compressor input power). Based on the modeling results and with estimating GEHP fuel consumption, the economic analysis of using gas engine heat pumps (in comparison with the electrical heat pumps) at various climate regions of Iran, for both residential and commercial (office) buildings, and for both cooling and heating modes, was performed. Appropriate cost functions for predicting GEHP capital investment were proposed. Three approaches including equivalent uniform annual cost (EUAC), the annual cost of energy consumption, and payback period were applied in the economic analysis.     

Economic and environmental evaluation of micro CHP systems with different operating modes for residential buildings in Japan

The growing worldwide demand for less polluting forms of energy has led to a renewed interest in the use of micro combined heat and power (CHP) technologies in the residential sector. The operation of micro CHP system results in simultaneous production of heat and power in a single household based on small energy conversion units. The heat produced may be used for space and water heating and possibly for cooling load if combined with an absorption chiller, the electricity is used within the house.In this paper, two typical micro CHP alternatives, namely, gas engine and fuel cell for residential buildings, are analyzed. For each facility, two different operating modes including minimum-cost operation and minimum-emission operation are taken into consideration by employing a plan and evaluation model for residential micro CHP systems. The analysis results show that the fuel cell system is recognized as a better option for the examined residential building from both economic and environmental points of view. With the operation considering optimal economic benefits, annual energy cost is reduced by about 26%. On the other hand, while maximizing the environmental merits, annual CO₂ emissions are reduced by about 9%.     

区域供冷供热冷热源方案的寿命周期成本分析

本文简要介绍了寿命周期成本的概念和寿命周期成本的分析方法,并利用该方法对大连市星海湾区域供冷供热项目的冷热源设计方案进行评价。分析表明,在大连地区采用溴化锂吸收式制冷机加热电厂方案的寿命周期成本最低,此外利用海水源热泵方案在商业电价下的寿命周期成本最高而在民用电价下的寿命周期成本比较低,考虑海水源热泵方案符合国家的可再生能源利用政策,本项目选定海水源热泵方案。     

居民用户天然气供暖方案

以包头市北部新区居民用户的天然气供暖方案为例,对比分析了燃气壁挂炉供暖、燃气壁挂炉与太阳能联合供暖、模块式燃气锅炉楼栋供暖、燃气区域锅炉房供暖、燃气热泵空调供暖、燃气冷热电三联供、天然气红外线辐射供暖7种供暖方案的技术特点,对比较适合居民用户供暖的前4种方案进行了工程建设造价和运行费用对比分析。燃气壁挂炉供暖方案工程造价最低,运行费用较少,节能效果较好;燃气壁挂炉与太阳能联合供暖方案工程造价最高,但其运行费用最少,节能效果最佳。     

电供热发展简析

指出电直接供热是能源的低效应用，但可以作为其他供热方式的补充或用于建筑局部供热。认为热泵和电蓄能供热是电供热的发展方向，提出要增强建筑节能和提高供热系统管理水平，倡导冷热电联供和多能源综合利用。     

燃气轮机冷热电联供系统优化与节能经济性研究

以满足冷、热、电负荷需求时能源运行成本最低为优化目标,建立了联供系统经济最优化模型。结合实际应用场合负荷需求验证了联供系统的节能性和经济性。指出联供系统最优化运行模式与电气价格比有关,当电气价格比较低时,分供系统运行更经济。分析了各性能参数对系统经济性的影响,结果表明燃气轮机发电效率、吸收式制冷机的制冷系数及烟气余热回收效率对联供系统的经济性影响较大。     

冷热电联供系统成本分摊法研究

根据以微型燃气轮机为动力源的冷热电联供系统的工作流程,建立了其热力学模型.通过对其能量利用过程的分析,引入可用(火用)和折合炯的概念.在综合考虑冷热电联供系统中制冷量和供热量占系统总可用能比例的基础上,建立了以折合(火用)概念为基础的冷热电分摊模型.该模型克服了现有其他方法存在的缺陷,较其他方法更合理、实用.     

Renewable energy options for buildings: Case studies

This paper deals with a novel approach to study renewable energy options for buildings to make them more efficient, more cost effective, more environmentally benign, and more technologically attractive. To demonstrate the application of this study, four buildings are chosen as case studies with two from the residential sector, one commercial/institutional building, and one industrial building. A ground source heat pump for heating and cooling, a solar water heater for space heating and/or hot water, and a photovoltaic panel to generate electricity are designed for these case studies. Attempt is made to design projects under hybrid systems combined from two technologies are developed for the above-mentioned four cases. Results obtained indicate that solar thermal option for hot water and space heating becomes the most cost effective one for all cases (e.g., $4956 for Cases 1 and 2 and $70,652 for Case 3, and $91,361 for Case 4). In addition, solar electricity through PVs is technologically the most suitable one to meet the electricity demand. The ground source heat pump option is quite attractive from the efficiency and environmental impact point of views although it requires installation and maintenance, etc. Finally, hybrid systems provide better advantages, such as higher efficiency, reduced cost, reduced emissions, etc.     

热源循环泵流量对热电联供系统优化运行影响

建立利用热网蓄热以促进风电消纳的热电联合优化运行模型,分析热源循环泵流量对热电联供系统运行经济性的影响。案例分析结果表明,循环泵日电费随相对流量减小而降低。相对流量87%~100%范围内,目标函数(热电机组的日运行费用、日市电费、日弃风罚款之和最小)不变。当相对流量降至86%后,目标函数不降反升,且增大幅度大于循环泵日电费降低幅度。受供水温度及供回水温差的限制,随着相对流量减小,日间热电机组制热功率受到限制。为了满足热电联合优化运行模型热平衡条件(总供热量等于总耗热量),夜间热电机组制热功率无法降低,热电机组发电功率居高不下,导致风电消纳受限,弃风电量增大。日弃风罚款随之增加,最终导致目标函数升高。相对流量为87%时,热电联供系统的日运行费用最低。     

热泵在燃气冷热电联供系统的应用

介绍了某生态园燃气冷热电联供能源站的技术方案。采用水源热泵利用夜间城市电网低谷电进行蓄冷、蓄热,白天用于供冷、供热,延长了燃气发电机组的运行时间,降低了运行成本,提高了供冷、供热的安全可靠性。     

水环热泵与空气源热泵节能性对比分析

结合工程实例,对天津地区某办公建筑分别采用带有辅助热源的水环热泵、空气源热泵空调系统进行供冷、供热的工艺流程进行了比较。分析了负荷率对两种空调系统功耗的影响,比较了两种空调系统的系统造价及运行费用。负荷率为80％～100％时,水环热泵空调系统的功耗升高速率较快。水环热泵空调系统的系统造价及运行费用均低于空气源热泵空调系统。     

Analysis of a combined photovoltaic–geothermal gas-fired absorption heat pump system in a Canadian climate

This study examines the technical feasibility of using a geothermal gas-fired absorption heat pump (A-GSHP) for space conditioning and domestic hot water heating in a Canadian climate. The A-GSHP is coupled to a photovoltaic (PV) system with battery storage intended to ensure the full autonomy of the heating, ventilating and air conditioning (HVAC) system from the electric grid. The system is modelled using TRNSYS with standard models and a new performance-based A-GSHP model, which accounts for part-load operation. Results indicate that the coefficient of performance (COP) is equal to 1.12, 0.55 and 1.79 for heating only, cooling only and simultaneous cooling and domestic hot water (DHW) heating, respectively. A 13.5 kWp PV array and a 400 kWh battery storage are necessary to provide the electrical power required to operate the A-GSHP and the associated HVAC system at all times without importing electrical energy from the grid.     

建筑一体化电热冷联产光伏组件能量特性研究

传统太阳能光伏或光热建筑一体化只能为建筑提供单一电能或热能。通过研究一种集成发电、集热、制冷3种功能的建筑一体化电热冷联产光伏组件,对其夏季工况下能量特性进行了实际检测。结果表明:白天,组件集热同时能有效降低光伏电池温度,组件工作温度高于环境温度约8~16℃,发电和集热效率分别为14.1%~13.7%和40.1%~15.7%;晴朗夜间,组件通过对流和辐射两种传热方式进行散热制冷,总制冷功率为26.0~268.5 W/m~2。电热冷联产光伏组件适合与热泵结合,为建筑提供所需能源。     

利用温频法对空调冷热源进行经济分析及选择

以天津某五星级酒店为例,采用温频法(BIN法)和费用年值法,比较土壤源热泵对传统型电制冷、集中供热组合和吸收式直燃机3种空调系统冷热源进行经济性分析。结果表明,虽然地源热泵初期投资最大,但是年运行费用在3种方案中最低,具有很好的经济性。     

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.     

别墅建筑的几种空调设计方案

介绍了可用于别墅建筑的风冷式盛大热泵空调机组系统，风冷热泵冷水机组系统、等方案，指出应根据不同的能源和气候条件，     

北京南站冷热电三联供系统探讨

介绍了北京南站冷热电三联供系统设计,包括方案选择、负荷计算、系统配置、运行策略、节能分析等。认为使用燃气内燃机比燃气轮机更具优势,建议在电力并网前提下采用以电定热原则确定系统设备容量配置。     

燃气机热泵系统不同联供运行模式一次能源利用率的分析

分析了燃气机热泵热电冷三联供系统节能的热力学原理及应用优势,探讨了不同季节采用不同的联供运行模式一次能源利用率PER的情况,并就影响PER的主要因素——废热回收率、热泵性能系数及用于发电的燃气能量占燃气总能量的比例的变动效应进行了模拟计算,给出了燃气机热泵不同联供运行工况下PER的对比及规律。