Heat Pump Installation Research Articles

Air-to-air heat pumps in real-life use: Are potential savings achieved or are they transformed into increased comfort?

This paper deals with individual air-to-air heat pumps in Danish dwellings and summerhouses and the question of to what extent they actually deliver savings of energy consumption. Results show that 20% of the expected reduction of electricity consumption is converted into increased comfort in the homes, including extended heating areas, keeping a higher temperature and a longer heating season and using the heat pump for air conditioning. Data include electricity consumption in 185 households before and after installation of heat pumps together with survey results of 480 households. Furthermore, 12 households were selected for in-depth analysis including technical inspection and qualitative interviewing. Especially for summerhouses, results indicate that on average there is no reduction in electricity consumption, as energy efficiency is counter balanced by increased comfort and changed heating practices. These results have to be taken into account when making long-term energy planning for a sustainable energy system.

Multi-injection rate thermal response test with forced convection in a groundwater-filled borehole in hard rock

Convection is shown in earlier studies to improve the thermal contact between heat exchanger and borehole wall in water-filled boreholes. This study investigates the effect of convection on the required borehole length for a ground-coupled heat pump installation. Artificial convection was induced by an ordinary groundwater pump during a multi-injection rate thermal response test (MIR-TRT). For comparison, a second MIR-TRT was performed without pumping of groundwater. The required borehole length was estimated for a ground-coupled heat pump installation supplying a Swedish single-family house. The estimates are based on the results from the MIR-TRTs for thermal conductivity and borehole resistance. The results show linear decrease in required borehole length with increasing heat input rate during the MIR-TRT without pumping of groundwater due to buoyancy-driven convection. An artificial convection stronger than buoyancy-driven convection during the MIR-TRT with pumping of groundwater reduced the required borehole length by 9 %–25 % depending on the heat input rate.

Impact of district heating and groundwater heat pump systems on the primary energy needs in urban areas

Abstract This work is focused on the planning of rational heating systems for urban areas. From the sustainability viewpoint, district heating is an important option to supply heat to the users in urban areas. The energy convenience of such option depends on the annual energy request, the population density and the efficiency in heat production. Among the alternative technologies, geothermal heat pumps (both open loop and closed loop heat pumps) play a crucial role. This paper aims to propose a procedure to select which users in an urban area should be connected with a district heating network and which ones should be heated through an alternative technology, in order to reach a globally optimal system from the energy viewpoint. The procedure proposes district heating as the initial choice for all the users. The users are then progressively disconnected to the network, according with the primary energy required to supply them heat, and the alternative technology is considered for disconnected users. Here, ground water heat pump is considered as the alternative technology. The total primary energy request is assumed as the objective function to be minimized. To reach this result, the exergetic cost of heat supplied through heat pumps system must be evaluated. Such evaluation is not trivial, as it must include proper analysis of both the district heating network and the alternative system. In the case of densely populated areas, an additional consideration is necessary: the subsurface thermal degradation caused by heat pump installations may affect the performances of surrounding installations. This impact is calculated through a thermo-fluid dynamic model of the subsurface. The application to an Italian town is considered as a test case. The optimal configuration of the overall urban heating system is obtained. This configuration corresponds to the minimum primary energy request to supply heat to all the users (those connected to the network and those using an alternative heating system).

Technical and economic calculation of combined heating and cooling systems vegetable store-solar greenhouse

We present a technical and economic assessment of the usage expediency of a combined system solar greenhouse-vegetable storage with a heat pump installation. We show the results obtained from a comparison of heat supply options for a solar greenhouse.

Heat pump installation and greenhouse effect

Heat pump installation and greenhouse effect

Life Cycle Analysis of a Geothermal Heatpump Installation and Comparison with a Conventional Fuel Boiler System in a Nursery School in Galicia (Spain)

Within the work lines in sustainable energy field of the EnergyLab Technology Centre (Vigo, Spain), associated with the technologies that are under investigation by this centre, it is developed a study about the Life Cycle Analysis (hereinafter, LCA) over a geothermal heatpump (hereafter, GSHP) installation in a nursery school in the province of Pontevedra (Galicia, Spain), and its comparison with the fuel boiler system prior to GHP. Thus, with the use of computer tools and following specific rules about the calculation of LCA, assessing the environmental impact of each system, and perform the appropriate comparison in order to quantify the savings emissions and the improvement in sustainability related to the replacement of diesel boiler system by the GSHP system.

Heat pump integration in a cheese factory

The aim of process integration is to increase the efficiency and to reduce the energy consumption, operating costs and CO2 emissions of an industrial process. The proposed methodology is applied to a real case study of a cheese factory with non-simultaneous process operations and uses the time average approach combined with restricted matches. This work focuses on appropriate heat pump integration and two different integration strategies are proposed. In the first option, process modifications and direct heat exchange between the process and heat pump streams are not allowed, which means that the integration of heat pumps has to be realized through intermediate heat transfer networks. On the contrary, in the second option, direct heat exchange and process modifications are possible. The results of both options are analyzed and compared for the French and German context. Depending on the industrial constraints and the location, it is shown that the final choice of new heat pump installations may be different. Saving potential in operating costs is higher for option 2 where the cost savings can be higher than 40% for both countries. Furthermore the potential CO2 emissions and primary energy savings are compared.

Ground source heat pumps: observations from United Kingdom ground thermal response tests

The United Kingdom is experiencing a period of rapid growth in the use of ground source heat pump systems. Most installations in the United Kingdom use vertical ‘borehole’ heat-exchanger arrays, the design of which depends on four parameters: formation thermal conductivity, formation heat capacity, heat-exchanger resistance and heat-exchanger grout material heat capacity. Conventionally, two of these parameters (conductivity and resistance) are obtained from a thermal response test carried out on a trial heat exchanger at the site of interest by fitting thermal response data to classical line-source heat conduction theory. This test method gives no information on the heat capacities of the formation and grout material and requires an assumption about the former to enable the heat-exchanger resistance parameter to be extracted. In this work, a new method is developed for extracting all four parameters using a trust-region search algorithm in conjunction with a detailed numerical model of the test heat exchanger. Results give excellent agreement between the fitted-model predictions of heat-exchanger outlet water temperature and measured outlet water temperature for 13 test cases. A further advantage of the method developed here is that it can be used with data sets that contain disturbances and discontinuities. Practical applications: Most of the ground source heat pump installations in the United Kingdom use vertical ‘borehole’ heat-exchanger arrays. The design of these arrays requires information about the rock formation thermal conductivity and volume specific heat capacity and the borehole heat-exchanger thermal resistance and grout material volume specific heat capacity. These design parameters are usually obtained from a thermal response test carried out on a trial heat exchanger at the site of interest. In this work, thermal response test results from 13 UK sites are presented and a new method for obtaining the four design parameters is developed and proposed.

Insights into the reliability of different thermal conductivity measurement techniques: a thermo-geological study in Mære (Norway)

Thermal response tests (TRTs) are used to measure the effective thermal conductivity in boreholes. The results serve as a basis for the dimensioning of commercial ground-source heat pump installations with closed loop systems. The study evaluated the reliability of TRTs performed in winter by comparing two TRTs carried out under very different winter weather conditions. A third TRT elucidated the influence of convection in wells with a higher heat input. Rock cores were analysed for quartz content and these results and the laboratory-measured thermal conductivity data were compared with the TRT results. This highlighted the importance of the distribution and orientation of minerals in the rock, and that a high quartz content does not necessarily give high thermal conductivity values. It is concluded that winter TRTs give useful results if additional temperature loggers are installed in anticipated fracture zones to detect groundwater flow and to survey the effect of infiltrating water.

Fully Coupled 3-D Conjugate Heat Transfer Algorithm for Borehole Heat Exchanger Performance Prediction

Quantitative three-dimensional prediction of the thermal performance of a vertical borehole heat exchanger (BHE) in a ground-source heat pump installation is sought. As BHE installation exhibits exceptionally disparate characteristic length scales, an alternative formation-fluid-thermal fully coupled algorithm is derived to quickly predict the 3-D temperature distributions. The time scale of the steady prediction is of order minutes. This simulation capability can be readily coupled to long-time (order months) unsteady simulation of an entire wellbore field. Algorithm prediction is validated by comparison with data from an instrumented commercial installation for a unique BHE conduit design, followed by illustrative design optimization or variation assessments.

Towards an integrated design of voluntary approaches and standardization processes: An analysis of issues and trends in the Italian regulation on ground coupled heat pumps

Despite the lack of specific incentives, ground coupled heat pump (GCHP) installations are booming in Italy both in the private and public sectors. Such rapid growth is coupled with increasing concern for environmental and technical performances since no comprehensive regulation and reliable standards currently exist. This paper discusses potential schemes aimed at balancing mandatory and voluntary requirements by using SWOT 1 Strengths Weaknesses Opportunities Threats. 1 -based techniques and examining the opinions of sectoral leaders. The analysis suggests that standardization and voluntary schemes are perceived as efficient and effective tools to encourage the greening of Italian GCHP-SME 2 Small and medium enterprise. 2 s in the short-term while laying the foundations for sustainable policies in the longer run. A potential scheme is discussed that was simulated by reflecting the supply-side of the market, and which involves process and product standards.

Energy Optimization of an Installation of Reversible Geothermal Heat Pump

Energy Optimization of an Installation of Reversible Geothermal Heat Pump

A quasi-steady state mathematical model of an integrated ground source heat pump for building space control

This paper is concerned with the development of a mathematical model, capable of describing the quasi-steady state performance of an integrated ground source heat pump, which is used for heating and cooling of an institutional building located in a Mediterranean climate. The model is structured on functional basis according to the heat pump vapour compression or primary circuit, a secondary ground loop circuit and a secondary building loop circuit. Heat pump heating and cooling capacities, as well as COP, are considered to be dependent variables and are estimated in the model using performance fitted maps. Independent variables include: compressor speed, circulation pump speeds, ground loop return temperature and building circuit return temperature. The model is validated using data from a full-scale ground source heat pump installation. The validated model is used to examine system capacity and performance sensitivity to different control optimisation strategies, including set-point control of room air temperature, room air bandwidth temperature, building loop return water temperature and building loop return bandwidth temperature.

Miniaturization of the Loop-Tube-Type Thermoacoustic Cooling System: Effect of the Installation Position of Heat Pump and Working Gas in the Tube

A loop-tube-type thermoacoustic cooling system uses heat energy as a power source. Therefore, it is possible to put a loop tube into practical use in different areas. Several reports have described total loop tube lengths greater than 3 m. Additional miniaturization is necessary to apply this system to electronic devices such as personal computers. As described herein, to realize a miniature loop tube, an A4-size loop tube (850 mm total length; 24 mm inner diameter) was designed. Furthermore, to assess this system's cooling properties, two experimental investigations were carried out. One is to elucidate the heat pump installation position. The other is to assess the working gas in the tube. An A4-size loop tube driven on the basis of those experimental results achieved cooling from room temperature to 0 °C.

Opportunities for the integration of absorption heat pumps in the pulp and paper process

Implementation of absorption heat pumps (AHPs) in a Kraft pulping process was studied using a new methodology for the optimal integration of those devices in a process. Two generic opportunities were identified for an energy and water optimized mill: (i) integration of a double lift chiller in the bleaching chemical making plant to produce chilled and hot water simultaneously, using MP steam as the driving energy and, (ii) installation of a single stage heat pump to concentrate the black liquor and produce useful hot water by upgrading heat from the bleaching effluent and using MP steam as driving energy. The principles of AHPs operation and their efficient integration into a process are described. The simple payback time (SPB) and net present value (NPV) were used to evaluate the interest of such implementations. Considering 63 $/MWh for the steam price, SPB of 2.7 and 1.7 years have been estimated for the two cases.

Geothermal heat pump noise control (cont.): Its all in the details.

The installation of a geothermal heat pump in the basement of a 1900 era home introduced significant noise and vibration to a bedroom above, which was discussed in detail in a previous conference. After mitigating the noise and vibration using piping isolation products, lower levels of noise and vibration still remained. This paper will discuss pursuits that were implemented and the very effective resolution for mitigating the noise and vibration that was generated by the heat pump.

Theoretical analyses of energy saving in a direct contact evaporative crystallization through the installation of heat pump

Utilization of heat pumps in various industrial technological processes is considered as an important approach to reduce the demand of energy. One of a prospective chemical processes for heat pumps being used is crystallization process. This work presents a theoretical analysis of the feasibility and potential use of a heat pump in direct contact evaporative crystallization process. This process has advantages compared to traditional open solar pond system for the extraction of mineral salts by producing additional amount of desalinated water. Principle schemes of the process were proposed and the needed calculations were performed. A noticeable saving in energy was obtained compared to that of the ordinary process (without introducing a heat pump). Effect of some process variables such as initial air temperature and humidity on the energy saving was investigated.

Estimation of Groundwater Flow Velocity and Its Application for the Installation of the Ground-coupled Heat Pumps in the Nobi Plain, Central Japan

Estimation of Groundwater Flow Velocity and Its Application for the Installation of the Ground-coupled Heat Pumps in the Nobi Plain, Central Japan

A new energy analysis tool for ground source heat pump systems

A new tool, suitable for energy analysis of vertical ground source heat pump systems, is presented. The tool is based on analytical equations describing the heat exchanged with the ground, developed in Matlab ® environment. The time step of the simulation can be freely chosen by the user (e.g. 1, 2 h etc.) and the calculation time required is very short. The heating and cooling loads of the building, at the afore mentioned time step, are needed as input, along with the thermophysical properties of the soil and of the ground heat exchanger, the operation characteristic curves of the system's heat pumps and the basic ground source heat exchanger dimensions. The results include the electricity consumption of the system and the heat absorbed from or rejected to the ground. The efficiency of the tool is verified through comparison with actual electricity consumption data collected from an existing large scale ground coupled heat pump installation over a three-year period.

Combining Building Renovation and Ground Source Heat Pump Installations for the Reduction of Greenhouse Gas Emissions: A Case Study in Vaasa Finland

Given the growing interest in ground source heat pump and distributed heating installations in general for the reduction of greenhouse gas emissions, technology implementation planning can benefit from the simultaneous consideration of building renovations. Here, a method for identifying and evaluating scenarios based on cost and greenhouse gas emissions is presented. The method is demonstrated for a case study in Vaasa Finland. The case study considers the insulation of the walls, roof, and base floor and the replacement of windows based on 2003 and 2010 Finnish building codes simultaneously with the possible replacement of existing heat sources with ground source heat pumps. Estimates of changes in heat demand for consecutive renovations are combined with data on renovation, installation, heating costs, and life cycle greenhouse gas emissions data for the current and proposed heat sources. Preferred scenarios are identified and evaluated by building type, construction decade, and current heating source. The results are then placed within the contexts of the Vaasa building stock and policy theory.