Residential heat pump installations: the role of vocational education and training

Meeting European emissions targets is reliant on innovative renewable technologies, particularly ‘renewable heat’ from heat pumps. Heat pump performance is driven by Carnot efficiency and optimum performance requires the lowest possible space heating flow temperatures leading to greater sensitivity to poor design, installation and operation. Does sufficient training and installer capacity exist for this technology? This paper situates the results of heat pump field trial performance in a socio-technical context, identifying how far installer competence requirements are met within the current vocational education and training (VET) system and considers possible futures. Few UK installers have formal heat pump qualifications at National Vocational Qualification (NVQ) level 3 and heat pump VET is generally through short-course provision where the structure of training is largely unregulated with no strict adherence to a common syllabus or a detailed training centre specification. Prerequisites for short-course trainees, specifically the demand for heating system knowledge based on metric design criteria, is limited and proof of ‘experience’ is an accepted alternative to formal educational qualifications. The lack of broader educational content and deficiencies in engineering knowledge will have profound negative impacts on both the performance and market acceptance of heat pumps. Possible futures to address this problem are identified.     

污水源热泵系统应用的节能减排分析

介绍了污水源热泵系统的工作原理及研究现状,以长沙市城市污水实测数据为例,精确计算了长沙市城市污水中可利用的能量,定量比较了污水源热泵系统与空气源热泵系统的节能性能,计算分析了污水热能回收系统的环保性能指标.研究表明:长沙市城市污水中储存的可利用冷(热)量很高;在相同的供热量和制冷量的条件下,污水源热泵空调系统比空气源热泵系统更节能;采用污水热能回收系统,CO2、SOx、NOx、粉尘等4种污染物的削减量特别大,对减轻大气污染具有很显著的效果.由此认为在长沙地区应用污水源热泵系统有明显的节能减排效果.     

Analysis of thermal well storage for solar collector—heat pump systems

The storage of solar heat in the earth beneath a building, using closed circuit heat storage wells with a solar collector and water-to-air heat pump, is analyzed. ‘Closed circuit’ means that the water is circulated only between the collector, well, and heat pump, not between the well and the soil. An iterative steady state simulation of annual performance is demonstrated, using equations which were developed for the heat flow rates to and from the well and for the heat storage in the soil surrounding the well. Design and cost analysis examples are solved.Thermal wells are one means to provide large (seasonal) heat storage capacity for retrofit solar installations at relatively low cost and without added space requirements.     

天津地区太阳能-土壤源复合式热泵系统性能研究

北方某些地区南于冷热负荷的不平衡性,单一的土壤源热泵系统受到限制。太阳能辅助土壤源热泵系统是一种有效利用可再生能源的系统形式。本文对天津地区太阳能辐射情况、建筑全年逐时冷热负荷量及复合热泵系统的制热机组效率进行研究,分析在天津地区太阳能-土壤源复合热泵系统的节能性。     

A comparative performance analysis of solar heat exchangers for solar hot water application under controlled laboratory conditions

The paper presents the experimental performance evaluation of a novel retrofit heat exchanger (‘SolaPlug’) developed for solar hot water storage applications. The performance of this system was compared with a traditional dual-coil (‘Coil’) solar cylinder under controlled operating conditions. The tests were conducted under different solar-simulated conditions with a 30 and 20 evacuated tube collector. The results showed that after a 6-h test period, the average water temperatures within the store for the ‘SolaPlug’ system were 58.8°C and 40.5°C at 860 and 459?W?m^?2, respectively, and for the ‘Coil’ system were 60.5°C and 40.6°C when a 30 tube collector was used. The performance of the ‘SolaPlug’ system was marginally better than the ‘Coil’ system under the low solar input condition. Under high insolation condition, the overall ‘SolaPlug’ system efficiency was found to be 4.3% lower than that of the ‘Coil’ system. The ‘SolaPlug’ heat exchanger rating was 222?W?K^?1.     

地源热泵的地热能利用方式及经济性分析

对地源热泵的工作原理及其地热能利用方式进行了分析。结合工程实例,对水源热泵系统、土壤源热泵系统和风冷热泵系统在技术性能和经济性能方面进行了对比,指出土壤源热泵系统是一种性能良好、可行、经济且无污染的热泵技术,值得推广使用。     

Data fusion heat pump performance estimation

The aim of the study was to develop improved measurements on heat pump performance. A model-based approach was combined with data fusion technique to estimate performance of a heat pump. These improved heat pump performance measurements implied fused measurement between direct and indirect measurements of compressor power and condenser load. Developed models of compressor power and condenser load used input data from building energy management system to produce measurements on the heat pump performance. The direct measurements were obtained by using the temperature and pressure measurements, while the indirect measurements were obtained using the electrical signal of the heat pump part load. The results showed a big need for use of different data sources to define real energy performance metrics. Further, the analysis on obtained measurements showed that indirect and fused measurements were more reliable than only direct measurement, particularly for the condenser load. Use of only direct measurements could result in higher estimation of electricity and heating energy consumption than the real consumption is. The analysis of fused measurements on the heat pump performance showed that such improved measurement could enhance heat pump performance verification.     

太阳能辅助热泵干燥技术及其研究进展

干燥物料需要消耗大量的能量。我国的干燥能耗占工业总能耗比例达到了12%。机械化程度低是我国干燥能耗大于发达国家的主要原因。将热泵技术应用于物料干燥节能效果明显,并且热泵干燥是一种温和的干燥方式,干燥产品品质好,干燥温度调节范围宽,干燥参数易于控制。相比于热泵干燥,太阳能干燥运行费用低,环境污染少,也得到了广泛的关注。把太阳能与热泵结合起来进行物料干燥相比原有单一热泵系统有较大改进和提高。论述了国内外太阳能辅助热泵干燥技术。     

The maximum coefficient of performance of thermoelectric heat pumps

The effect of three main irreversibilities existing in thermoelectric devices on the performance of a thermoelectric heat pump is investigated. The coefficient of performance and the heating load of the heat pump are derived. The optimal performance of the heat pump at maximum coefficient of performance is discussed, and the rational working region of the heat pump is determined. The optimal structure of the device is also described. The results obtained here are more realistic than those derived from nonequilibrium thermodynamics.     

1st Environmental conference of Thessaly region, 8–10 September 2012, Hotel Skiathos Palace,Koukounaries, Skiathos Island,Greece

This study was conducted with the aim to assess the potential performance of a photovoltaic thermal mechanical ventilation heat recovery (PV/T MVHR) system. The device is currently considered for the application to the Z-en house project undertaken by Scottish homebuilder. The house’s whole energy demand was calibrated based on the UK Government’s standard assessment procedure for energy rating of dwellings, while the PV/T performance was estimated using an ‘EESLISM’ energy and environmental design simulation tool developed by Kogakuin University. This study concluded that PV generates heat, which makes the fresh air running under the PV roof 10–15?°C warmer than the outside temperature even during the Scottish winter and this warm air extracted from roof-integrated PV modules can be used to help reduce the domestic space-heating demand. Thus, the building-integrated PV/T MVHR system was considered as one of the effective means to assist the net zero energy operation of housing in cool and cold climates, whose dominant domestic energy comsumption derives from space heating.     

夏季工况空气-土壤源热泵系统能效分析

采用试验方法,针对夏季工况,对空气-土壤源热泵机组分别在单纯空气源热泵运行模式、单纯土壤源热泵运行模式、空气-土壤源热泵运行模式下的制冷性能系数、能效比进行了实测比较。空气-土壤源热泵运行模式下的制冷性能系数、能效比较高,有利于改善土壤热平衡。     

宾馆热泵热水系统的试验研究

探讨了适用于宾馆的热泵热水系统的加热方式及水箱布置形式。结合工程实例,对不同卫生热水温度下的热泵制热性能系数及不同水箱布置形式的热泵热水系统耗电量进行了试验研究。在宾馆使用热泵制备卫生热水可行。在选择合适的冷凝器卫生热水进出口温差以提高热泵制热性能系数时,应优化水箱布置形式,减少循环泵数量及其能耗,以提高热泵热水系统的制热性能系数。     

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.     

分布式蓄热罐容量优化及二级管网调节改进

介绍分布式蓄热、二级管网调节方法研究现状,对分布式蓄热罐容量优化及二级管网调节方法改进途径进行综述。国内外均重视分布式蓄热、二级管网调节方法的研究。采用蓄热罐在带来良好经济效益的同时,还能实现节能减排,蓄热罐容量对供热系统的经济性存在较大影响。对分布式蓄热罐容量进行优化,是提高供热系统经济性的有效方法。在热网的运行调节方面,变频泵技术受到了广泛关注,对变频泵变流量调节与分布式蓄热系统相结合的优化研究还比较缺乏。     

太阳能热泵供热系统性能的试验研究

对太阳能热泵系统的不同运行工况进行了试验研究。分析了蒸发器入口水温、冷凝器入口水温对热泵系统性能的影响。通过研究分析得出:太阳能集热器面积与热泵机组的匹配为影响系统性能的重要参数,应根据用户对热量的需求来选择;蒸发器入口水温可在5℃—20℃之间变化,在20℃时,系统COP最高达到3.6。通过对试验结果的分析,为太阳能热泵系统的设计和运行控制提供了依据。     

Comparison between design and actual energy performance of a HVAC-ground coupled heat pump system in cooling and heating operation

This work compares the experimental results obtained for the energy performance study of a ground coupled heat pump system with the design values predicted by means of standard methodology. The system energy performance of a monitored ground coupled heat pump system is calculated using the instantaneous measurements of temperature, flow and power consumption and these values are compared with the numerical predictions. These predictions are performed with the TRNSYS software tool following standard procedures taking the experimental thermal loads as input values. The main result of this work is that simulation results solely based on nominal heat pump capacities and performances overestimate the measured overall energy performance by a percentage between 15% and 20%. A sensitivity analysis of the simulation results to changes in percentage of its input parameters showed that the heat pump nominal coefficient of performance is the parameter that mostly affects the energy performance predictions. This analysis supports the idea that the discrepancies between experimental results and simulation outputs for this ground coupled system are mainly due to heat pump performance degradation for being used at partial load. An estimation of the impact of this effect in energy performance predictions reduces the discrepancies to values around 5%.     

太阳能辅助CO_2热泵系统回热器设计及实验研究

在CO2跨临界循环系统中,节流损失相对较大。通过增加回热器的方法以提高跨临界CO2热泵系统的COP。根据相关的换热关联式对CO2热泵系统的回热器进行了设计计算并且进行了相关的实验研究。计算得到的回热器,长度为1.27 m,内管内径6 mm,外管内径13 mm,壁厚1 mm。并且在相同环境工况下,利用自行搭建的CO2热泵系统实验台,分别在有回热器与无回热器时进行了实验研究。实验结果表明:当系统引入回热器后,压缩机排气压力、温度上升,压缩机耗功上升速率加快,制热量增加速率亦加快,且制热量增加速率大于压缩机耗功增加速率,系统制热COP增加,带回热器时系统平均COP达到3.34,无回热器时系统平均COP为3.03,提高约10.2%。     

Simulation and analysis on thermodynamic performance of surface water source heat pump system

This work established a thermodynamic performance model of a heat pump system containing a heat pump unit model, an air conditioning cooling and heating load calculation model, a heat exchanger model and a water pump performance model based on mass and energy balances. The thermodynamic performance of a surface water source heat pump air conditioning system was simulated and verified by comparing the simulation results to an actual engineering project. In addition, the effects of the surface water temperature, heat exchanger structure and surface water pipeline transportation system on the thermodynamic performance of the heat pump air conditioning system were analyzed. Under the simulated conditions in this paper with a cooling load of 3400 kW, the results showed that a 1 °C decrease in the surface water temperature leads to a 2.3 percent increase in the coefficient of performance; furthermore, an additional 100 m of length for the closed-loop surface water heat exchanger tube leads to a 0.08 percent increase in the coefficient of performance. To decrease the system energy consumption, the optimal working point should be specified according to the surface water transportation length.     

直膨式太阳能热泵系统仿真

随着太阳能热利用和热泵技术的成熟及商品化,直膨式太阳能热泵技术将太阳能资源的清洁性、可再生性等特点和热泵系统的节能、高效的优点相结合,极具研究价值。但是目前直膨式太阳能热泵不能产品化推广的主要限制因素是系统设计不合理、运行不稳定、整体性能不佳等问题。现以直膨式太阳能热泵系统的优化和设计匹配为研究目标,同时,建立压缩机、集热器/蒸发器、热力膨胀阀、冷凝器及储热水箱的数学模型。从理论上分析集热器中集热面积、太阳能辐照度、环境温度、压缩机容积及冷凝温度等因素对直膨式太阳能热泵系统热工性能的影响,通过系统仿真及实验研究系统的整体热力性能,并在此基础上给出改善系统性能的建议。     

热流密度对垂直地埋管群周围土壤温度的影响

地埋管群换热器的换热特性很大程度上决定了地源热泵系统的性能,其中U型埋管群周围土壤的温度特性主要受到排列形式、埋管深度、地上负荷特性以及土壤传热系数等参数的影响。通过实验来定性分析热流密度的改变对埋管群周围土壤的过余温度以及热响应时间造成的影响,为地下埋管群的设计及优化提供参考。