Field Of Heat Pumps Research Articles

Data-based, high spatiotemporal resolution heat pump demand for power system planning

Decarbonizing the residential building sector by replacing gas boilers with electric heat pumps will dramatically increase electricity demand. Existing models of future heat pump demand either use daily heating demand profiles that do not capture heat pump use or do not represent sub-national heating demand variation. This work presents a novel method to generate high spatiotemporal resolution residential heat pump demand profiles based on heat pump field trial data. These spatially varied demand profiles are integrated into a generation, storage, and transmission expansion planning model to assess the impact of spatiotemporal variations in heat pump demand. This method is demonstrated and validated using the British power system in the United Kingdom (UK), and the results are compared with those obtained using spatially uniform demand profiles. The results show that while spatially uniform heating demand can be used to estimate peak and total annual heating demand and grid-wide systems cost, high spatiotemporal resolution heating demand data is crucial for spatial power system planning. Using spatially uniform heating demand profiles leads to 15.1 GW of misplaced generation and storage capacity for a 90% carbon emission reduction from 2019. For a 99% reduction in carbon emissions, the misallocated capacity increases to 16.9-23.9 GW. Meeting spatially varied heating load with the system planned for uniform national heating demand leads to 5% higher operational costs for a 90% carbon emission reduction. These results suggest that high spatiotemporal resolution heating demand data is especially important for planning bulk power systems with high shares of renewable generation.

Effects of secondary fluid flow rate on cooling performance of vapor compression systems

The vapor compression cooling devices operate on the same principle as heat pumps. In these types of machines thermal energy is transferred from the cold environment to the warmer side using provided power by the compressor. In this study, the effect of air flow rate on the cooling performance of vapor compression cooling devices has been investigated by simulating a designed system in AVL CRUISE™ M program. The simulated model is air-to-air cooling machine and refrigerant R134a was used as circulated gas inside the system. COP value of the system has been calculated in different working conditions and obtained results have been fully discussed. Accordingly, enthalpy variation in every element of the heat pump has been calculated in different working conditions and discussed on P-h diagram. This study presents a simulation method that is a practical solution method in the field of heat pumps, cooling machines and refrigerators which can be considered before installing device in order to have a proper prediction of the system performance.

The concept of low-cost didactic rig in the field of heat pumps

The Centre of Sustainable Development and Energy Saving in Miękinia conducts broad didactic activities for various groups of students. For its own purposes, and also as a concept to use for other didactic centers, a low-cost didactic stand in the scope of heat pumps was designed and implemented. The constructed device presents the operating principles and schematically describes the basic elements of the ground source heat pump system. The device was constructed using a used piston and hermetic compressor from an old fridge. As an evaporator and condenser, a heat exchanger made from copper pipe curved meandering was used. A carefully selected capillary tube was used as an expansion element. The distribution of the components and the visualization of the didactic rig were devised. The whole concept assumed the usage of propane (R290) as an ecological refrigerant. The project also includes cost statements for creating an alternative to a commercial, low-cost stand for teaching purposes at various levels of education and suggests ways of using the set.

The addition of heat pump electricity load profiles to GB electricity demand: Evidence from a heat pump field trial

Previous studies on the effect of mass uptake of heat pumps on the capability of local or national electricity grids have relied on modelling or small datasets to create the aggregated heat pump load profile. This article uses the UK Renewable Heat Premium Payment dataset, which records the electricity consumption of nearly 700 domestic heat pump installations every 2minutes, to create an aggregated load profile using an order of magnitude more sites than previously available. The aggregated profile is presented on cold and medium winter weekdays and weekends and is shown to contain two peaks per day, dropping overnight to around 40% of its peak. After Diversity Maximum Demand (ADMD) for the population of heat pumps is calculated as 1.7kW per site; this occurs in the morning, whereas the peak national grid demand occurs in the evening. Analysis is carried out on how heat pump ADMD varies with number of heat pumps in the sample. A simple upscaling exercise is presented to give a first order approximation of the increase in GB peak electricity demand with mass deployment of heat pumps. It is found that peak grid demand increases by 7.5GW (14%) with 20% of households using heat pumps. The effect of the same heat pump uptake on grid ramp rate is also discussed; this effect is found to be minor. Finally, a comparison of heat pump and gas boiler operation is given, discussing day and night time operation and mean and peak power at different external temperatures.

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.

A review of heat pump systems for heating and cooling of buildings in China in the last decade

Heat pump technology fully shows the principle of energy recycling in terms of Heating, Ventilating and Air Conditioning (HVAC). It avoids unipolarity of energy using in the conventional HVAC system. Heat pumps use high-grade energy as a driving energy, recovering and upgrading low-grade energy for avail, like a pump. Because heat source used in HVAC usually is low temperature heat, heat pump systems adopted in HVAC will help improve heating performance coefficient. Therefore, HVAC is one of ideal users of heat pump applications, and thus high-grade energy used in HVAC can be replaced with a large number of low-temperature renewable energy. Through the heat pump technology, natural low-grade energy stored in the soil, water, air or waste heat from variant industries and daily lives, is supplied for building cooling/heating and hot water serving. Therefore, vast applications and developments of heat pump technology are presented in HVAC in China, and some progresses are achieved in the system innovation, experimental research, product development and engineering application, etc. This paper reviews the progress of researches, applications and development in the field of heat pumps for building cooling/heating in China since the 21st century.

Validation of a black-box heat pump simulation model by means of field test results from five installations

In the residential sector, heat pumps are applied for domestic hot water and space heating. Simulations are widely used for general research in the field of heat pumps and to some extend to plan such installations. The advantages are low expenditure of time and costs compared to laboratory or field tests.Validation of simulation models is mandatory to guarantee a sufficient quality. In the presented paper, the field monitoring results of five ground-source installations are utilised for the validation of a black-box heat pump model. The model is similar to TRNSYS Type 201, but implemented in IDA ICE and then modified to handle the difficulties caused by non-standard mass flow and rampant polynomials. As overall result, deviations between 1% and 32% regarding modelled and measured efficiency are seen on monthly basis. The overall result appears as convincing, taking into account typical inaccuracies of laboratory and field tests as well as tolerances during heat pump production.As a side effect, the influence of standby consumption was quantified. For the five presented installations, standby amounts to fractions between 2 and 5% of the annual electricity consumption of the heat pump units.

Meta-analysis of European heat pump field trial efficiencies

A meta-analysis of seasonal performance for ground to water and air to water heat pumps based on eight European trials for over 600 installations from five countries provides thirteen different descriptors of performance. Seven of these trials have previously been publish but no overview of their results has been attempted in terms of system boundary analysis. Trial boundaries are rationalised to four values of seasonal performance providing the opportunity to reassess the UK EST heat pump trial results and identify two boundary conditions directly relevant to the interpretation of the Renewable Energy Sources Directive. What is apparent is the wide range in performance at all boundaries and in all trials indicating that heat pumps are sensitive to design and installation practice. The overarching theme of the paper is the need for a unified framework for reporting heat pump performance and its applicability to the re-analysis of existing data. The task of building such a framework has proved beyond the present author, but the work presented here represents an attempt to scope the potential value and combination of analytical and practical difficulties that would need to be faced by those undertaking such a task.

Domestic heat pumps in the UK: user behaviour, satisfaction and performance

Consumer adoption of microgeneration technologies is part of the UK strategy to reduce carbon emissions from buildings. Domestic heat pumps are viewed as a potentially important carbon saving technology, given the ongoing decarbonisation of the electricity supply system. To address the lack of independent evaluation of heat pump performance, the Energy Saving Trust undertook the UK’s first large-scale heat pump field trial, which monitored 83 systems in real installations. As part of the trial, the Open University studied the consumers’ experience of using a domestic heat pump. An in-depth user survey investigated the characteristics, behaviour, and satisfactions of private householders and social housing residents using ground source and air source heat pumps for space and/or water heating, and examined the influence of user-related factors on measured heat pump system efficiency. The surveys found that most users were satisfied with the reliability, heating, hot water, warmth and comfort provided by their system. Analysis of user characteristics showed that higher system efficiencies were associated with greater user understanding of their heat pump system, and more continuous heat pump operation, although larger samples are needed for robust statistical confirmation. The analysis also found that the more efficient systems in the sample were more frequently located in the private dwellings than at the social housing sites and this difference was significant. This is explained by the interaction between differences in the systems, dwellings and users at the private and social housing sites. The implications for heat pump research, practice and policy are discussed.

Evaluation of a field test with retrofit heat pumps

The efficiency of electrically driven compression heat pumps for existing dwellings has been evaluated with the help of data from a field test of E.ON Energie AG, conducted through the Fraunhofer Institute for Solar Energy Systems in Freiburg. The data has been verified and grouped to allow for a detailed analysis.This analysis of the heat pump field test shows that evaluable data exist for 43 out of 77 field test objects. Of these 43 objects, 21 are air-to-water heat pumps, 17 are brine-to-water heat pumps with horizontal ground source heat exchangers, and 5 are brine-to-water heat pumps with vertical ground source heat exchangers. A mean seasonal performance factor of 2.3 for air-coupled devices and 2.9 for ground-coupled devices shows that applying heat pumps (installed 2007) of various manufacturers in existing buildings is questionable with respect to primary energy savings and CO2 emissions. Therefore, the performance data of heat pumps is compared to condensing boilers with a fuel utilization efficiency of 0.96. Different fuel utilization efficiencies are calculated, as well as different primary energy and emission conversion factors.The best systems achieved seasonal performance factors of 3.0 (air) and 4.0 (ground-coupled). The great difference to the mean values illustrates the high potential of this technology on the one hand and the necessity to optimize the total system on the other.

CO 2 heat pump systems

After the CFCs and the HCFCs were deemed unfit as working fluids in refrigeration, air conditioning, and heat pump applications, there has been a renaissance for carbon dioxide technology. Heat pumps is one of the application areas where theoretical and experimental investigations are now performed by an increasing number of research institutions and manufacturers. This paper gives an overview of some of the current activities in the CO 2 heat pump field. Discussed are the important characteristics of the transcritical CO 2 process applied to heat pumps, and also discussed are theoretical and experimental results from several heat pump applications. Provided that calculations and system designs are performed on the premises of the working fluid, and that test plants are constructed and operated to fully exploit the specific characteristics of both the fluid and the transcritical process, the results show that CO 2 is an attractive alternative to the synthetic fluids. Competitive products may be launched in the near future.

The discrepancy between heat pump field and test performance: A simulation study

A discrepancy is reported whereby laboratory measurements of the COPh of air-to-water heat pumps yield performace data which are significantly inferior to seasonal values as measured in the field. A mechanism is proposed to account for this and example calculations show that improvements of up to 20 per cent can be expected over normal laboratory estimates.