Metal hydride heat pumps

Heat pumps have been known for a long time, but, until the energy crisis of 1973, there were only a few studies covering them. Since that time, in addition to alternative energy sources, scientists and engineers have started studying heat pumps more earnestly. There are several kinds of heat pump and utilizations of them, but the most common one is the vapour-compression heat pump. In recent years researchers have started to study metal hydride heat pumps. The paper considers the metal hydride bed, its thermodynamics, and its utilization as a heat pump. It is also compared with conventional heat pumps. The results indicate that the metal hydride heat pump has several advantages, and its utilization in the industrial, commercial and residential fields is foreseen.     

Experimental characterization of two Pumps As Turbines for hydropower generation

In recent years, the use of turbines or Pumps operating As Turbines (PATs) has been proven to be a sustainable alternative for managing Water Distribution Networks (WDNs), by coupling pressure control and leakage reduction with hydropower generation.Pumps running in reverse mode can be an effective alternative to using turbines for energy production in WDNs. Many commercial models are readily available on the market and a number of economic and technical advantages for installation, operation and maintenance can be found. Theoretical and experimental criteria for predicting pump performance in turbine mode and for the optimal installation of a PAT in WDNs can be found in the literature. Nevertheless, the prediction of PAT characteristic curves is still an unresolved issue, because of the lack of information provided by manufacturers and the few laboratory campaigns that focus on the topic.For this purpose, the laboratory results in the present study aim to assess the performance of pumps operating in reverse mode. Two centrifugal pumps were investigated: a centrifugal horizontal single-stage pump and a vertical multi-stage pump. Experiments were compared with theoretical models available in the literature, in order to assess their reliability in predicting PAT performance when data are lacking.     

Integration of absorption heat pumps in a Kraft pulp process for enhanced energy efficiency

A preliminary feasibility study of the implementation of various absorption heat pump configurations in a Kraft pulping process has been performed. Three different cases were considered: (i) integration of a double lift heat transformer into the heat recovery circuit of the wood chips digesters to produce low pressure steam equivalent to 25% of the steam demand of the chemical pulping plant, (ii) a double effect chiller installed in the bleaching chemicals making plant to chill cooling water and produce middle pressure steam and, (iii) a heat pump installed on the steam extraction line of a turbine which, combined with the addition of a condensing unit, increases substantially the power output. The simple payback time and net present value were used to compare the three cases. Both indices are highly dependant upon steam prices. The net present value is, in all cases, positive, which indicates that the equipment is viable using the assumed cost and efficiency data in this study. Absorption heat pumps are increasingly attractive options for energy upgrading and conversion in a context of increasing energy costs.     

300MW机组汽动给水泵组存在问题与改进

引进型300MW汽轮机组配有2台50％容量汽动给水泵,本文以鹤岗2号机组为例,针对汽动给水泵组经常发生的一些问题,提出了具体的建议和改进措施。     

基于CFD混流式水轮机上冠转轮泵结构优化研究

为研究中高水头混流式水轮机上冠转轮泵工作特性及优化可行性,以红山嘴一级电站3号水轮机为例,建立现转轮泵及11种结构优化模型,利用CFD商业软件,基于SST湍流模型对不同结构转轮泵在9种流量工况下展开数值模拟。将上冠流道泄漏水流动特性、主轴密封真空度及转轮泵效率作为研究指标,结果表明：上冠流道泄漏水流动特性依赖于转轮泵的结构类型;减小转轮泵“泵盖高度比”或斜置动泵叶对提高主轴密封真空度均有显著效果(最佳结构可提高66.9%),同时须兼顾其工作效率;额定工况下,转轮泵工作效率较低,建议转轮上冠开设合适的泄水孔补给流量提高其效率;该电站可将泵叶斜置45°、泵盖高度比H_p=0.0543的转轮泵作为最佳改进方案。     

Energy and exergy analysis of fossil plant and heat pump building heating system at two different dead-state temperatures

In this paper, we deal with the energy and exergy analysis of a fossil plant and ground and air source heat pump building heating system at two different dead-state temperatures. A zone model of a building with natural ventilation is considered and heat is being supplied by condensing boiler. The same zone model is applied for heat pump building heating system. Since energy and exergy demand are key parameters to see which system is efficient at what reference temperature, we did a study on the influence of energy and exergy efficiencies. In this regard, a commercial software package IDA-ICE program is used for calculation of fossil plant heating system, however, there is no inbuilt simulation model for heat pumps in IDA-ICE, different COP (coefficient of performance) curves of the earlier studies of heat pumps are taken into account for the evaluation of the heat pump input and output energy. The outcome of the energy and exergy flow analysis at two different dead-state temperatures revealed that the ground source heat pumps with ambient reference have better performance against all ground reference systems as well as fossil plant (conventional system) and air source heat pumps with ambient reference.     

Experimental study of operation performance for hydrocarbon fuel pump with low specific speed

In this paper,a small flow rate hydrocarbon turbine pump was used to pressurize the fuel supply system of scramjet engine.Some experiments were carried out to investigate the characteristics of turbine pump driven by nitrogen or combustion gas under different operating conditions.A experimental database with regard to the curves of the rotational speed,mass flow rate and net head with regard to centrifugal pump were plotted.These curves were represented as functions of the pressure and temperature at turbine inlet/outlet and the throttle diameter at downstream of centrifugal pump.A sensitivity study has been carried out based on design of experiments.The experimental was employed to analyze net head of centrifugal and throttle characteristics.The research results can accumulate foundations for the close loop control system of turbine pump.     

Performance study of solar water pump using packed-bed collectors

In the present investigation solar water pumps using packed-bed collectors have been developed. It has been experimentally observed that the performance behaviour of such pumps is much superior to that of a solar water pump using conventional plain collectors. Among the solar water pumps developed, the one using iron-turning packed-bed collectors exhibits the best performance. It is interesting to conclude that the performance of a solar water pump using conventional (plain) collectors can be improved appreciably just by packing the collectors with metallic materials.     

Theoretical model for evaluation of variable frequency drive for cooling water pumps in sea water based once through condenser cooling water systems

In sea water based once through cooling water system for power plants, sea water is pumped through the condenser and the return hot water is let back to sea. The cooling water pumps (CWP) in power plants generally operate at constant speed, pumping variable quantities of water depending on the tide level in the sea. The variable flow causes variation in condenser back pressure resulting in changes in the turbine cycle heat rate. If the pump speed is controlled using a variable frequency drive (VFD) to maintain design flow irrespective of the tide level, the CWP power consumption can be reduced compared to the case with constant speed CWP. However, the turbine cycle heat rate benefit that could have accrued at tide levels above the pre defined level (for fixing the CWP head) with constant speed CWP would have to be sacrificed. This paper provides a theoretical model with a typical case study to establish viability of providing VFD for CWPs in power plants with sea water based once through condenser cooling water system.     

Performance analysis of a heat pump assisted drying system

The paper describes a simulation model developed to predict the performance of drying systems assisted by vapour-compression heat pumps. The heat is used to preheat the air stream before it enters the drying chamber. Energy consumption is thus reduced, as the heat pump is capable of delivering more energy as heat than it in fact consumes as input work. Ambient air provides the heat source. A computer program, based on simplified modelling of components (compressor, heat exchangers and drying chamber) has been developed. Results have been produced for a typical application, revealing that a considerable reduction in energy consumption can be obtained with the use of a heat pump. The effect of air flow rate on system performance is also studied.     

Performance of centrifugal pumps running in reverse as turbine: Part Ⅱ- systematic specific speed and specific diameter based performance prediction

This paper, Part II of a two part paper, presents a comprehensive correlation aimed to bring out the accurate prediction of the turbine mode operation of centrifugal pumps. This work uses experimental data of wide range of pumps representing the centrifugal pump configurations in terms of specific speed. Based on specific speed and specific diameter an accurate correlation is developed to predict the performances at best efficiency point of the centrifugal pump in its turbine mode operation. The proposed prediction method yields very good results to date compared to previous such attempts. The present method is compared to nine previous methods found in the literature. The comparison results show that the method proposed in this paper is the most accurate. The proposed method can be further complemented and supplemented by more future tests to increase its accuracy. The proposed method is meaningful because it is based on both specific speed and specific diameter.     

热泵工艺在油田注水站的应用分析

热泵系统也称余热回收系统,是使用部分驱动能源(如燃气、蒸汽、燃气或热水),将余热形式为地热水、冷却水、洗涤水或伴油污水,温度在20~70℃的低品位能量取出,转移到45~100℃的中高温热媒中的系统。热泵系统在利用低品位热能的同时,仅消耗少量电能,节能效果显著。我国直到20世纪90年代,开始大面积应用热泵技术。目前,在热泵制造、安装和运行规模上,已走到了国际前例。现在,不管是压缩式热泵,还是吸收式热泵,也不论是设备还是系统,其技术已经成熟,热泵机组制热温度达到45~100℃,COP值(能量与热量之间的转换比率,简称能效比)也达到相当高的水平,机组的超小型化和超大型化技术得到长足发展,被广泛应用到建筑、烘干、石油化工、医药、筑路等领域。以热泵工艺在油田注水站的应用为分析对象,针对热泵的起源、发展、工作原理及在注水站的应用展开论述,着重从初期投资、运行费用、人工费用、社会效益、节约清水及10年费用现值方面,对注水站采用热泵冷却工艺与常规冷却工艺进行对比分析,提出了注水站采用热泵工艺有利于提高注水站系统的热能效率,降低运行成本,减少加热炉加热过程中产生的废气和余热排放,实现节能减排,对于热泵工艺在大庆油田注水站的应用具有借鉴意义。     

中高温热泵技术在工业余热回收中的应用

我国许多行业对热源的需求温度多集中在75～200℃之间，且存在着低温余热大量浪费的情况，可以把热能由低温位热源转移到高温位热源的中高温热泵技术有着巨大的应用空间。对高温热泵的研究多集中在适宜工质的选择和制热效率提高这两个方面。国外的研究起步较早，混合工质方面的研究成果目前仍处于技术保密阶段。国内研究起步较晚，主要研究成果集中在高校，但尚未找到一种公认的环境友好、性能优越的高温热泵工质。近几年，国内在油田含油污水的余热回收．坑口电厂冷却水和矿井涌水的余热回收，涂装、电镀车间余热回收等领域进行了高温热泵技术的实际性工程应用，经济效益和环保显著．不仅节省了大量的化石能源，而且减少了二氧化碳的排放。但高温热泵技术在实际应用中还存在设备腐蚀等问题．需要结合余热源的具体情况采取相应的措施加以解决。     

Experimental and numerical investigation on application of half vane diffusers for centrifugal pump

Vaned diffusers are widely used in centrifugal pumps, but little research has been published regarding action mechanism and the influence of diffuser vane height on dynamics performance of centrifugal pumps. Experimentally and numerically, the present investigation was focused on the dynamics performances of a low specific speed centrifugal pump equipped with vane diffusers with different vane heights. The pump performance was appraised when the diffuser vane height (h/b) was 0 (vaneless), 0.5, 0.6, 0.8 and 1 (vaned) times the diffuser width respectively. The pressure fields were numerically simulated in order to study the influence of half vane diffusers on inner flow field. The experimental results of operating performance showed that the efficiency was significantly improved for 2.5% at design flow point and the head was significantly improved for nearly 3 m at over flow point. The best efficiency point shifted towards higher flow rate with h/b reducing, and the high efficiency area was broadened by using half vane diffusers. Besides, half vane diffusers could reduce the intensity of pressure fluctuations at the leading edge of the stator vanes, and reduce the influence of rotor-stator interaction in tongue region. The numerical results showed that half vane diffusers could enhance flow uniformity in pumps, symmetry of pressure distributions on the impeller outlet and preferable regularity of radial force distributions. Therefore, it is very useful and feasible to apply half vane diffusers in centrifugal pumps.     

Financial evaluation of renewable energy technologies for irrigation water pumping in India

An attempt to develop a simple framework for financial evaluation of renewable energy technologies (RETs) such as photovoltaic (PV) pump, windmill pump, biogas and producer gas-driven dual fuel engine pumps for irrigation water pumping has been made. The unit cost of water and unit cost of useful energy delivered by the RETs have been estimated. The monetary benefits that accrued to the end-user have been quantified in terms of the amount of diesel or electricity saved. Financial figures of merit for the investments made in the RETs have been estimated. The effect of fuel price escalation on these measures of financial performance has also been evaluated along with the estimation of the break-even prices of fuels likely to be substituted by RETs. Results of some exemplifying calculations are presented and briefly discussed.     

A photovoltaic-powered system for medium-head pumping

A prototype photovoltaic-powered pumping system capable of supplying 15 m³ of water per day in full sunlight at heads of around 35 m has been developed. Design criteria are based on requirements for drinking water supplies to small villages in tropical countries.The system consists of a well-known and widely used pump (the Mono^®† progressive cavity pump) driven by a very efficient dc motor with long brush life, which is supplied with power from a dc-dc converter. The power source is a 800 W photovoltaic array. Laboratory testing of the whole system shows that it is reliable and has an overall sunlight to pumped-water efficiency in excess of 3%. This is comparable to the highest efficiencies that have been reported elsewhere for solar powered pumps. The system behaves well at heads other than the design head (35 m) and has been tested over the range 25 to 55 m. Simulations of the volumes of water pumped during standard solar days of 4 kWh/m² and 5 kWh/m² have enabled comparisons to be made with published tests on other solar powered pumps. The present system easily meets the established criteria.     

Multi-objective optimization of a multi water-to-water heat pump system using evolutionary algorithm

This paper deals with the energy recovery in the dairy industry. Thermodynamic, economic and environmental optimization of three water-to-water heat pumps has been studied in order to replace totally or partially a fuel boiler used to produce heat at different temperature levels in a cheese factory. These heat pumps have their evaporators connected to one effluents source and two of them are equipped by storage tanks at the condenser side. Multi-objective optimization permits optimal repartition of mass flow rates of effluents and optimal choice of electrical power of the compressors and volumes of storage tanks. The thermodynamic objective is based on the exergy destruction in the whole system. The economic objective is based on the investment cost and the operating cost obtained with the heat pump system. The environmental impact objective has been defined and expressed in cost terms by considering a CO₂ taxation (carbon tax) on the GHG emissions. This objective has been integrated with the economic objective. Multi-objective genetic algorithms are used for Pareto approach optimization.     

Comparison of energy and exergy analysis of fossil plant,ground and air source heat pump building heating system

The energy and exergy flow for a space heating systems of a typical residential building of natural ventilation system with different heat generation plants have been modeled and compared. The aim of this comparison is to demonstrate which system leads to an efficient conversion and supply of energy/exergy within a building system.The analysis of a fossil plant heating system has been done with a typical building simulation software IDA–ICE. A zone model of a building with natural ventilation is considered and heat is being supplied by condensing boiler. The same zone model is applied for other cases of building heating systems where power generation plants are considered as ground and air source heat pumps at different operating conditions. Since there is no inbuilt simulation model for heat pumps in IDA–ICE, different COP curves of the earlier studies of heat pumps are taken into account for the evaluation of the heat pump input and output energy.The outcome of the energy and exergy flow analysis revealed that the ground source heat pump heating system is better than air source heat pump or conventional heating system. The realistic and efficient system in this study “ground source heat pump with condenser inlet temperature 30 °C and varying evaporator inlet temperature” has roughly 25% less demand of absolute primary energy and exergy whereas about 50% high overall primary coefficient of performance and overall primary exergy efficiency than base case (conventional system). The consequence of low absolute energy and exergy demands and high efficiencies lead to a sustainable building heating system.     

轻型柴油机共轨系统高压泵CB18的开发

为满足轻型柴油机经济型共轨系统的需求,开发了CB18共轨高压泵。多项创新设计使CB18的性能和成本满足设计要求。机油润滑的直列泵比柴油润滑的径向泵更适合中国的实际应用条件。上下叠加的双球阀实现了理想的性价比。平缓上升+先缓后急下降+基圆停留的凸轮型线适应了共轨泵的运转特点。滚轮摩擦副发热烧伤是共轨泵特有的失效机理,通过类金刚石涂层工艺得到解决。CB18共轨高压泵在许多发动机上得到应用,成为国内第1个大批量走向市场的本土开发的共轨部件。     

PG9171E燃气轮机用辅助润滑油泵的设计与性能优化

现阶段PG9171E燃气轮机用辅助润滑油泵存在成本高、故障率高等缺点,因此亟需自主设计、本土化生产的辅助润滑油泵取代,以降低燃气轮机的工作成本。本文介绍了上海电力公司闸北发电厂燃气轮机专用LYT230-90型辅助润滑油泵的设计方案,该泵可将流量增加15%,电机输出轴与辅助润滑油泵齿轮的同心度降低到0.05mm,大幅提升了其运行平稳性。