Energy-saving judgment of electric-driven seawater source heat pump district heating system over boiler house district heating system

As a renewable energy utilization system, the electric-driven seawater source heat pump district heating system is gaining popularity in some coastal areas. However, under what conditions can the system achieve its energy-saving effect and how to evaluate its energy-saving potential are not clear in practice. In this paper, an expression of the critical COP value of the heat pump unit for energy-saving (COP_h,c) is derived through the comparison of the system and the conventional boiler house district heating system in the energy consumption respect. On the other hand, the actual COP values of the heat pump unit (COP_h,a) are calculated by an experimental data regression model on the basis of the manufacturer's dataset. The comparison of the values of COP_h,c and COP_h,a makes the energy-saving judgment of an electric-driven seawater source heat pump district heating system and its energy-saving potential, if it has, readily available. It was found that both the heating district radius and the natural conditions of the seawater are the most important factors that determine the energy efficiency of the system. And through comparison, it was also found that the type of the fuel of the boiler has significant impact on the crucial index value of COP_h,c.     

Study on the performance of a solar assisted air source heat pump system for building heating

This paper proposed a new solar assisted air source heat pump system with flexible operational modes to improve the performance of the heating system. A mathematical model was established on the solar assisted air source heat pump system for building heating with a heating capacity of 10 kW, and an air source heat pump unit was developed to validate the model. The effect of the solar collector area on the performance of the system running in Nanjing was studied. The results showed that the COP of the heat pump unit was enhanced with the increase of the solar radiation density during the typical sunny day in the heating season. In addition, the COP also increased in proportion to the solar collector area. Compared with the case when the solar collector area was 0 m², the COP increase of the heat pump and the energy-saving rate were 11.22% and 24% respectively when the solar collector area was 40 m². Meanwhile, the solar equivalent generation power efficiency could reach 11.8%.     

Exergetic cost analysis of a space heating system

In order to evaluate and improve the design of space heating systems with groundwater source heat pumps (GWHP), common design practices should be examined. In this paper, a GWHP system with common design is studied. The COP of the heat pump is 3.5 at design condition. The system is divided into five subsystems, and exergetic cost analysis is performed on it based on structural theory of thermoeconomics. The results show that the three largest relative exergy destructions and lowest exergy efficiencies occur in power generation and distribution, heat pump, and terminal unit subsystems with relative exergy destructions of 71.2%, 17.1% and 7.02% and exergy efficiencies of 32.8%, 54.8% and 65.6% respectively. The three subsystems also have the largest increases of unit exergetic costs of 2.04 W/W, 2.15 W/W, and 2.73 W/W respectively. Therefore, designers of GWHP space heating systems should pay close attention to heat pump and terminal unit subsystems, especially to the latter one because of its larger increase of unit exergetic cost. The unit exergetic cost of the system final exergetic product is 7.92 W/W. This value can be used to evaluate the system and compare it with others from the viewpoint of energy conservation.     

A theoretical study of an innovative ejector enhanced vapor compression heat pump cycle for water heating application

This study presents a novel vapor compression heat pump cycle in which an ejector associated with a subcooler is applied to enhance the heating performance for air-source heat pump water heater application. The heating coefficient of performance (COP_h) and heating capacity of the novel cycle using the non-azeotropic mixture refrigerant R417A are theoretically investigated, for the ranges of evaporating temperature (−15 to 10 °C) and condensing temperature (55-60 °C). The theoretical results show that the COP_h and volumetric heating capacity of the novel cycle are better than that of the conventional heat pump cycle. It is found that for the operating conditions considered, the maximum COP_h and volumetric heating capacity can be improved by up to 1.62-6.92% and 15.20-37.32% over the conventional heat pump cycle, respectively. The performance characteristics of the novel cycle show its promise in air-source heat pump water heater applications.     

曹妃甸工业区浅层地源热泵系统方案分析

对地源热泵进行了介绍,分析了曹妃甸工业区浅层地源热泵系统方案,指出地源＋海水源热泵系统能够充分发挥曹妃甸工业区的地域资源优势,而且具有明显的长期运行技术经济优势。     

Performance analysis of a solar-assisted ground-source heat pump system for greenhouse heating: an experimental study

This study investigates the performance characteristics of a solar-assisted ground-source (geothermal) heat pump system (SAGSHPS) for greenhouse heating with a 50 m vertical 32 mm nominal diameter U-bend ground heat-exchanger. This system was designed and installed in the Solar Energy Institute, Ege University, Izmir (568 degree days cooling, base: 22 °C, 1226 degree days heating, base: 18 °C), Turkey. Based upon the measurements made in the heating mode from the 20th of January till 31st of March 2004, the heat extraction rate from the soil is found to be, on average, 57.78 W/m of bore depth, while the required borehole length in metre per kW of capacity is obtained as 11.92. Design practices in Turkey normally call for U-bend depths between 11 and 13 m/kW of heating. The entering water temperature to the unit ranges from 8.2 to 16.2 °C, with an average value of 14 °C. The greenhouse air has a maximum day temperature of 31.05 °C and night temperature of 14.54 °C with a relative humidity of 40.35%. The heating coefficient of performance of the heat pump (COP_HP) is about 2.00 at the end of a cloudy day, while it is about 3.13 at the end of sunny day and fluctuates between these values in other times. The COP values for the whole system are also obtained to be 5–20% lower than COP_HP. The clearness index during experimental period is computed as average 0.56. At the same period, Cucumus sativus cv. pandora F₁ was raised, and product quality was improved with the climatic conditions in the designed SAGSHPS. However, experimental results show that monovalent central heating operation (independent of any other heating system) cannot meet the overall heat loss of the greenhouse if the ambient temperature is very low. The bivalent operation (combined with other heating system) can be suggested as the best solution in Mediterranean and Aegean regions of Turkey.     

District heating system design for a university campus

İzmir Institute of Technology campus is in use since 2000 and still under development. At present, heating is provided by individual fuel boilers. On the other hand, the campus has a geothermal resource in its borders with a temperature of 33 °C. Because of this low geothermal fluid temperature; heat pump district heating system is considered for the campus. As an alternative, fuel boiler district heating system is studied. Each heating system is simulated using hourly outdoor temperature data. For the simulations, a control system with constant flow rate and variable return water temperature is used and the main control parameter is the indoor temperature. Various heating regime alternatives have been studied for heat pump district heating system for the various condenser outlet temperature and geothermal fluid flow rate, and two of these alternatives are given in this study. Furthermore, economic analysis has also been done for each heating system alternative based on investment and operational costs. Results indicate that heat pump district heating system has the highest investment but lowest operational cost.The alternatives are evaluated according to internal rate of return method, which shows the profit of the investment and resulted that, the heat pump district heating system has minimum 3.02% profit comparing with the fuel boiler district heating system at the end of the 20-year period.     

A techno-economic comparison of ground-coupled and air-coupled heat pump system for space cooling

This paper reports a techno-economic comparison between a ground-coupled heat pump (GCHP) system and an air-coupled heat pump (ACHP) system. The systems connected to a test room in Firat University, Elazig (38.41°N, 39.14°E), Turkey, were designed and constructed for space cooling. The performances of the GCHP and the ACHP system were experimentally determined. The experimental results were obtained from June to September in cooling season of 2004. The average cooling performance coefficients (_COPsys${\mathrm{COP}}_{\mathrm{sys}}$) of the GCHP system for horizontal ground heat exchanger (HGHE) in the different trenches, at 1 and 2 m depths, were obtained to be 3.85 and 4.26, respectively and the _COPsys${\mathrm{COP}}_{\mathrm{sys}}$ of the ACHP system was determined to be 3.17. The test results indicate that system parameters can have an important effect on performance, and that GCHP systems are economically preferable to ACHP systems for the purpose of space cooling.     

谈暖通空调节能问题与地源热泵的实际应用

针对暖通空调节能问题进行了研究,结合实际案例介绍了地源热泵在工程项目中的应用,通过与以城市供热为热源的室内散热器取暖方案进行对比分析,得出地源热泵系统能够有效解决空调系统节能问题,值得推广。     

Theoretical simulation and experimental research on the system of air source energy independence driven by internal-combustion engine

Presents a new system of air source energy independence driven by internal-combustion engine (EIICE), which used natural gas or other fuels as an independent input energy, and could provide the heating, cooling and hot water for the buildings efficiently. It also could provide electricity for electric equipments of the system. The performance of air source EIICE system was investigated theoretically and experimentally. The experimental and simulation results indicated that the heat capacity of plate heat exchanger (P-HE), heat recovered from exhaust gas heat exchanger (EG-HE), input power of compressor, output power of engine and fuel consumption increased with the increase of the rotary speed, water flow rate of the P-HE and evaporation temperature. Heat recovered from the cylinder jacket heat exchanger (CJ-HE) increased with the increase of the rotary speed and evaporation temperature, but decreased with the increase of the water flow rate of P-HE. The coefficient of performance (COP_t) and primary energy ratio (PER_t) of air source EIICE system also increased with the increase of the water flow rate of P-HE and evaporation temperature, but decreased with the increase of the rotary speed.     

中德两国大型区域供热系统的结构性差异与启示

从热源、调峰锅炉加输配站、输送管网、楼栋换热站、室内供暖系统等环节介绍了德国海德堡市的大型区域供热系统。经分析、比较中德两国的供热系统,发现德国的区域供热系统具有以下特点:1)清洁环保、高效供热;2)热用户可以自主选择高标准舒适供暖和全年使用集中生活热水;3)其高效输配系统既可节省初投资,又能降低水系统输配能耗,还巧妙地解决了管网的水力平衡问题;4)优良的调节性能使其供热系统既能适应天气的变化,又能有效地适应用户调节引起的流量变化,供热企业主要通过变流量调节实现供热系统节能;5)整体的经济技术保证措施使得热计量行为节能目标得到彻底落实;6)严格精细的保温规定为减少热输送过程中的热损失提供了可靠保证。     

热电厂间接连接供暖系统能耗分析

以佳木斯市一新型墙体节能建筑小区供暖系统作为研究对象,通过对典型小区换热站的实际耗热量、耗电量和耗水量的统计和处理,分析了该类型供暖小区的供暖能耗水平,用实际供暖效果和数据验证了供暖系统的运行调节方法的效果和可行性。     

A heat pump system with a latent heat storage utilizing seawater installed in an aquarium

This paper introduces a heat pump system with a latent heat storage utilizing seawater installed in an aquarium. Heat from the seawater is collected and used as the heat source for the heat pump system. This maintains the indoor conditions at constant temperature and relative humidity. With regard to the heat pump system using low-temperature unutilized heat source, development is introduced on a heat source load responsive heat pump system, with combines a load variation responsive heat pump utilizing seawater with a latent heat (ice plus water slurry) storage system using nighttime electric power serving for electric power load leveling. The desired outcome would be to show that the costs of generating heat energy with the seawater-source heat pump are significantly less than those with the air-source heat pump and the oil-fired system. Additionally, the CO₂ emissions for the seawater-source heat pump compare favourably as they maybe less than those for the other conventional assumed systems described.     

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。     

浅谈海水源热泵施工的监理工作

结合具体工程实例,对海水源热泵系统作了简单介绍,重点对海水源热泵安装与调试过程的监理工作进行了阐述,通过管理控制,保证了系统质量,进而体现了海水源热泵的节能优势。     

空气源热泵辅助加热太阳能泳池系统设计

通过工程实例介绍了空气源热泵辅助太阳能泳池加热系统的工作原理、系统原理图以及运行控制策略,通过节能技术的组合,以达到节能减排的效果,并尽可能实现工程投资经济和系统运行安全的最佳组合。     

Exergoeconomic evaluation on the optimum heating circuit system of Simav geothermal district heating system

Simav is one of the most important 15 geothermal areas in Turkey. It has several geothermal resources with the mass flow rate ranging from 35 to 72 kg/s and temperature from 88 to 148 °C. Hence, these geothermal resources are available to use for several purposes, such as electricity generation, district heating, greenhouse heating, and balneological purposes. In Simav, the 5000 residences are heated by a district heating system in which these geothermal resources are used. Beside this, a greenhouse area of 225,000 m² is also heated by geothermal. In this study, the working conditions of the Simav geothermal district heating system have been optimized. In this paper, the main characteristics of the system have been presented and the impact of the parameters of heating circuit on the system are investigated by the means of energy, exergy, and life cycle cost (LCC) concepts. As a result, the optimum heating circuit has been determined as 60/49 °C.     

海水源热泵区域供热系统最大供热半径的研究

在国家建筑节能设计标准中的耗电输热比EHR的基础上引申得到了热水循环泵输送能耗与系统供热量的一次能耗比EHR'指标,并根据对海水源热泵区域供热系统EHR'指标的不同控制要求,得到了系统的最大供热半径.经计算,当热水供回水温差为10℃,海水源热泵区域供热系统的EHR'指标分别控制在5%,10%,15%,20%时,系统的最大供热半径应分别为0.875,2.75,4.625,6.5 km.     

谈集中供热系统节能技术

结合我国北方地区集中供热的发展现状,从供热系统的组成部分:热源、热网和热用户三个方面,简单分析了如何提高供热系统的能源利用率,有效降低供热能耗,从而达到节能减排的目的。     

Development of system concepts for improving the performance of a waste heat district heating network with exergy analysis

The building sector is responsible for a great share of the final energy demand and national CO₂ emissions in countries like Germany. Nowadays, low quality thermal energy demands in buildings are mainly satisfied with high-quality sources (e.g. natural gas fired in condensing boilers). Exergy analysis, pursuing a matching in the quality level of energy supplied and demanded, pinpoints the great necessity of substituting high-quality fossil fuels by other low quality energy flows, such as waste heat. In this paper a small district heating system in Kassel (Germany) is taken as a case study. Results from preliminary steady-state and dynamic energy and exergy analysis of the system are presented and strategies for improving the performance of waste-heat based district heating systems are derived. Results show that lowering supply temperatures from 95 to 57.7 °C increases the final exergy efficiency of the systems from 32% to 39.3%. Similarly, reducing return temperatures to the district heating network from 40.8 to 37.7 °C increases the exergy performance in 3.7%. In turn, the energy performance of all systems studied is nearly the same. This paper shows clearly the added value of exergy analysis for characterising and improving the performance of district heating systems.