The importance of utilizing different types of energy and their technical application is discussed. Awareness around the globe about the world energy crisis and its critical environmental condition has put more emphasis on the use of renewable energies in every corner of life. It is a well‐known fact that global warming, inefficient use of energy and greenhouse gases are damaging the environment, species and human life drastically. These issues will be discussed in recently conducted research. To address the crucial state of our environment, two simultaneous scenarios are considered. Initially, energy conservation and the switch to a low carbon/no carbon fuel are studied. As for energy conservation in buildings, smart methods in the use of energy in buildings are discussed. Based on different research reported, humans must change their attitude toward the use of resources, and in particular, be conscientious about energy consumption. Next, renewable energy promises a suitable alternative to energy needs in this century, and the best means to overcome the environmental issue and energy crisis is discussed. The practical methods of calculation for solar technology equipment, ground source heat pumps, and wind turbines are explained. In the application part of the study, four buildings are chosen as case studies; two of them from residential sectors, one is a commercial/institutional building, and the fourth is an industrial building. A ground source heat pump for heating and cooling, a solar water heater for heating space or hot water, and a photovoltaic panel for generating electricity are designed for the case studies. Even projects under hybrid systems combined from two technologies are designed. 36 different energy options are calculated for the four case studies. Results show that if a target is reducing CO2 emissions, what systems are the best. In contrast, when decision making is based on budget, what system is the first choice? Not only are technology, environmental protection and cost the main parameters for deciding on renewable technologies, but so are reliability, installation, maintenance and ease of use. Hence, renewable energy systems are categorized based on a broad vision.

Closed-loop ground source heat pumps (GSHPs) are used to transfer thermal energy between the subsurface and conditioned spaces for heating and cooling applications. A basic GSHP is composed of a ground heat exchanger (GHX), which is a closed loop of pipe buried in the shallow subsurface circulating a heat exchange fluid, connected to a heat pump. These systems offer an energy efficient alternative to conventional heating and cooling systems; however, installation costs are higher due to the additional cost associated with the GHX. By further developing our understanding of how these ground loops interact with the subsurface, it may possible to design them more intelligently, efficiently, and economically. To gain insight into the physical processes occurring between the GHX and the subsurface and to identify efficiencies and inefficiencies in GSHP design and operation, two main research goals were defined: comprehensive monitoring of a fully functioning GSHP and intensive simulation of these systems using computer models. A 6-ton GSHP was installed at a residence in Elora, ON. An array of 64 temperature sensors was installed on and surrounding the GHX and power consumption and temperature sensors were installed on the system inside the residence. The data collected were used to help characterize and understand the function of the system, provide motivation for further investigations, and assess the impact of the time of use billing scheme on GSHP operation costs. To simulate GSHPs, two computer models were utilized. A 3D finite element model was employed to analyse the effects of pipe configuration and pipe spacing on system performance. A unique, transient 1D finite difference heat conduction model was developed to simulate a single pipe in a U-tube shape with inter-pipe interactions and was benchmarked against a tested analytical solution. The model was used to compare quasi-steady state and transient simulation of GSHPs, identify system performance efficiencies through pump schedule optimization, and investigate the effect of pipe length on system performance. A comprehensive comparison of steady state and pulsed simulation concludes that it is possible to simulate transient operation using a steady state assumption for some cases. Optimal pipe configurations are identified for a range of soil thermal properties. Optimized pump schedules are identified and analysed for a specific heat pump and fluid circulation pump. Finally, the effect of pipe spacing and length on system performance is characterized. It was found that there are few design inefficiencies that could be easily addressed to improve general design practice.

Ground source heat pumps (GSHP) are efficient alternatives to air source heat pumps to provide heating and cooling for conditioned buildings. GSHPs are widely deployed in the midwest and eastern regions of the United States but less so in Texas and the southwest regions whose climates are described as being semi-arid. In these semi-arid regions, building loads are typically cooling dominated so the unbalance in energy loads to the ground, coupled with less conductive soil, cause the ground temperature to increase over time if the ground loop is not properly sized. To address this ground heating problem especially in commercial building applications, GSHPs are coupled with supplemental heat recovery/rejection (SHR) systems that remove heat from the water before it is circulated back into the ground loops. These hybrid ground source heat pump systems are designed to reduce ground heating and to lower the initial costs by requiring less number of or shallower boreholes to be drilled. This thesis provides detailed analyses of different SHR systems coupled to GSHPs specifically for residential buildings. The systems are analyzed and sized for a 2100 ft2 residential house, using Austin, Texas weather data and ground conditions. The SHR systems investigated are described by two heat rejection strategies: 1) reject heat directly from the water before it enters the ground loops and 2) reject heat from the refrigerant loop of the vapor compression cycle (VCC) of the heat pump so less heat is transferred to the water loop at the condenser of the VCC. The SHR systems analyzed in this thesis are cooling towers, optimized VCC, expanded desuperheaters and thermosyphons. The cooling towers focus on the direct heat rejection from the water loop. The VCC, desuperheater, and thermosyphon systems focus on minimizing the amount of heat rejected by the VCC refrigerant to the water loop. In each case, a detailed description of the model is presented, a parametric analysis is provided to determine the amounts of heat that can be rejected from the water loop for various cases of operation, and the practical feasibility of implementation is discussed. An economic analysis is also provided to determine the cost effectiveness of each method. / text

The PhD thesis focuses on the performance assessment of permeable pavement systems incorporating ground source heat pumps (GSHP). The relatively high variability of temperature in these systems allows for the survival of pathogenic organisms within the sub‐base. Salmonella sp, Escherichia coli, Enterococci and total heterotrophic bacteria were analysed in order to assess potential risk to health. Supplementary carbon dioxide monitoring indicated relatively high microbial activity on the geotextile and within the lower parts of the sub‐base. Anaerobic processes were concentrated in the space around the geotextile, where carbon dioxide concentrations reached up to 2000 ppm. The overall water treatment potential was high, with up to 99% biochemical oxygen demand removal. Variable removal efficiencies have been calculated for nutrients such as ortho‐phosphate‐phosphorus, ammonia and nitrates/nitrites. Calculated Coefficients of Performance and Energy Efficiency Rates provided evidence on correctness of GSHP design. Collected data was analysed with non‐parametrical statistics and a self‐organizing map model was used to assess relationships between variables. Findings present correlations considered as low and insignificant between temperature fluctuations and pathogen numbers. Highly significant correlations (p<0.01) were calculated for influent‐effluent relationships. Air and water temperatures and water quality data variability within the systems provided evidence for the high level of biological processes leading to a low risk of pathogen transition to human.

Closed-loop ground source heat pumps (GSHPs) are used to transfer thermal energy between the subsurface and conditioned spaces for heating and cooling applications. A basic GSHP is composed of a ground heat exchanger (GHX), which is a closed loop of pipe buried in the shallow subsurface circulating a heat exchange fluid, connected to a heat pump. These systems offer an energy efficient alternative to conventional heating and cooling systems; however, installation costs are higher due to the additional cost associated with the GHX. By further developing our understanding of how these ground loops interact with the subsurface, it may possible to design them more intelligently, efficiently, and economically. To gain insight into the physical processes occurring between the GHX and the subsurface and to identify efficiencies and inefficiencies in GSHP design and operation, two main research goals were defined: comprehensive monitoring of a fully functioning GSHP and intensive simulation of these systems using computer models. A 6-ton GSHP was installed at a residence in Elora, ON. An array of 64 temperature sensors was installed on and surrounding the GHX and power consumption and temperature sensors were installed on the system inside the residence. The data collected were used to help characterize and understand the function of the system, provide motivation for further investigations, and assess the impact of the time of use billing scheme on GSHP operation costs. To simulate GSHPs, two computer models were utilized. A 3D finite element model was employed to analyse the effects of pipe configuration and pipe spacing on system performance. A unique, transient 1D finite difference heat conduction model was developed to simulate a single pipe in a U-tube shape with inter-pipe interactions and was benchmarked against a tested analytical solution. The model was used to compare quasi-steady state and transient simulation of GSHPs, identify system performance efficiencies through pump schedule optimization, and investigate the effect of pipe length on system performance. A comprehensive comparison of steady state and pulsed simulation concludes that it is possible to simulate transient operation using a steady state assumption for some cases. Optimal pipe configurations are identified for a range of soil thermal properties. Optimized pump schedules are identified and analysed for a specific heat pump and fluid circulation pump. Finally, the effect of pipe spacing and length on system performance is characterized. It was found that there are few design inefficiencies that could be easily addressed to improve general design practice.

Interest in indirect (secondary) refrigeration systems has grown since the discovery of the negative effect of environmentally hazardous refrigerants and leakage problems from direct expansion systems. Among the positive effects of indirect systems are: decreased quantities of primary refrigerant, factory built units and confinement of refrigerant to the machine room. Ground source heat pumps, ice rink and indirect system solutions for supermarket refrigeration are examples where indirect refrigeration systems are being used in Sweden. The secondary fluids circulating in the secondary systems are of great interest as its choice can affect heat transfer process; the overall performance of system; corrosion problems and maintenance costs as well as acceptable risks for the environment in case of leakage from the secondary system. A secondary fluid should have low viscosity, high thermal conductivity, high volumetric heat capacity, low freezing point, be non-corrosive, non-explosive, non-flammable, environmentally friendly, non-toxic, give low pressure drop in the system, have good material compatibility, chemically stable and have low cost. The market for secondary fluids worldwide and in Sweden is complex and a comprehensive overview of the available secondary fluids has not been available. The purpose of this thesis is to compile most of the existing secondary fluids on the Swedish market and present them briefly in this report. Different brands of secondary fluids on the Swedish market based on ethylene and propylene glycol, ethyl alcohol, potassium formate, potassium acetate, calcium chloride and other blends are presented in the thesis. Some of the most common brands are: Eco MPG, Dowcal 200, Dowcal N, Zitrec FC, Zitrec LC, Antifrogen L, Frigogel Neo, Heliogel CS80, Brineol MPG, Glytherm 20, Zitre MC, Dowcal 100, Antifrogen N, Neutragel Neo, Brineol MEG, Glytherm 10, Antifrogen Sol HT, Freezium, Hycool, Antifrogen KF, Brine 25, Swedbrine 25, Brenntag KBS, Brineol Bioethanol, E-Therm KBS Bio, Thermol, Zitrec S, Temper, Pekasol 50, Pekasol 2000, Greenway RTU, Greenway Heat Pump -30, greenway Solar -30, Thermera R and Thermera AC. Additionally, it is important to underline that a permit for installation of ground source heat pumps in Sweden is required. Swedish laws and regulations regarding secondary fluids and ground source heat pumps are complex and difficult to overview on municipalities’ levels.

Nowadays, Ground Source Heat Pumps (GSHPs) are more frequently acting as a main or the only device covering the building heat/cool demand. The most efficient way to extract/dissipate the low-temperature heat from/to the ground is by means of Borehole Heat Exchanger (BHE). In this Master of Science Thesis various aspects related to this technology are studied, focused on summarizing the possibilities of installing this tech-nology in Poland. Borehole drilling methods used in Poland and Sweden are analyzed and the most proper and economical ones according to Polish geological structure are proposed. Approximately for 80 % of Poland the ground should be penetrated with Mud Rotary Drilling, while for the rest 20 % DTH Air or Water driven hammer should be used. Solutions of Thermal Insulated Leg (TIL) Borehole Heat Exchanger cooperation with mechanical ventilation system are proposed and simple preliminary estimations show higher Coefficient of Performance (COP) in comparison to normal, common situation, where standard U-pipe BHE works. The possibility of using a new product (Energy Capsule - EC) in Polish conditions is surveyed, found hard to prosper at Polish market according to its high costs. Profitability of Ground Source Heat Pumps with Borehole Heat Exchanger in different geological regions of Poland is investigated. After conducted simulations it occurred that Polish lowland regions are cheaper in exploita-tion, while uplands regions are less expensive at investment level. Finally, the most ef-ficient BHE conception from those currently available at market as well as recently in-vented is suggested. Annular coaxial BHE in a form of Energy Capsule seems to be the most beneficial from all designs taken into account during performed simulations because of its low price and good thermal properties.

The aim of this thesis is to increase the understanding of small-scale green energy technology development. In the transition towards a fossil free energy system, heat pumps are a low emission heating alternative. Contrary to other types of new small-scale green energy technology such as solar cells and electric vehicles, heat pumps are established on the Swedish market, with more than half the share of single family buildings. This makes it possible to study an example of a mature technology, and that knowledge could be used in the development and deployment of other technologies with similar small-scale green characteristics. The type of heat pump technology studied is ground source heat pumps, and their development is explored from an economic and performance perspective, using the concept of learning. Learning tracks how a product develops for each doubling of units produced. The results show that the efficiency has increased by a learning rate of 2.8 %. When the effects of a low-temperature heating system is included, the learning rate is even higher, 5.8 %. The efficiency improvement is mainly due to new and more expensive components, which has resulted in a price increase. Even if the price slightly decreased until 2008, it has increased with 29 % since. Nevertheless, the ground source heat pump is profitable compared to several other heating technologies. The most important factors underpinning the development are regulations, competition among manufacturers and research.

The Ground Source Heat Pump systems (GSHP) are an emerging technology used to exchange heat with the ground through the use of some buried heat exchangers. The thermal response of a borehole field can be characterized by its g-function. It is a non-dimensional temperature response factor, which can be calculated using either numerical or analytical solutions. Eskilson developed the first study made for the calculation of these g-functionts. Lamarche and Beauchamp proposed another analytical approach based on the Finite Line Source (FLS). Generally, both solutions present similar results with some small differences. They could be attributed to the boundary condition performed in both researches: the FLS solution considers uniform heat flux along the borehole wall in all the heat exchangers, while Eskilson’s model defines as a condition, uniform temperature at the borehole wall within all the pipes in the field. In this Master of Science Thesis, the temperature response factors (g-functions) of a 6x6 borehole field with 36 heat exchangers (BHE) arranged in a squared configuration are obtained from new numerical models, mainly based on the use of a highly conductive material composing the BHE. For this purpose, a commercial software called Comsol Multyphisics© is employed. The aim of this thesis is to get larger knowledge in generating the g-function in relation to the boundary condition performed in the model trying to reach better approximations to the reality. Some strategies with respect to the geometry, size of the model and mesh are performed to reduce the computing time. The influence of the geothermal heat flux and the influence of the highly conductive material (HCM) composing the BHEs are also studied in our model. Going further, the thermal behavior of the ground is also studied by imposing variable heating and cooling loads during seasonal periods over a time of 25 years. Finally, the g-functions obtained from our numerical models are compared to the one generated with the commercial software, Earth Energy Design (EED), which represents the numerical solution proposed by Eskilson, and the one generated with FLS approach. The results may explain in a closer approximation to the reality the thermal response for large borehole fields.

<p>The sales of Ground Source Heat Pumps in Sweden and many other countries are having a rapid growth in the last decade. Today, there are approximately 360 000 systems installed in Sweden, with a growing rate of about 30 000 installations per year. The most common way to exchange heat with the bedrock in ground source heat pump applications is circulating a secondary fluid through a Borehole Heat Exchanger (BHE), a closed loop in a vertical borehole. The fluid transports the heat from the ground to a certain heating and/or cooling application. A fluid with one degree higher or lower temperature coming out from the borehole may represent a 2-3% change in the COP of a heat pump system. It is therefore of great relevance to design cost effective and easy to install borehole heat exchangers. U-pipe BHEs consisting of two equal cylindrical pipes connected together at the borehole bottom have dominated the market for several years in spite of their relatively poor thermal performance and, still, there exist many uncertainties about how to optimize them. Although more efficient BHEs have been discussed for many years, the introduction of new designs has been practically lacking. However, the interest for innovation within this field is increasing nowadays and more effective methods for injecting or extracting heat into/from the ground (better BHEs) with smaller temperature differences between the heat secondary fluid and the surrounding bedrock must be suggested for introduction into the market.</p><p>This report presents the analysis of several groundwater filled borehole heat exchangers, including standard and alternative U-pipe configurations (e.g. with spacers, grooves), as well as two coaxial designs. The study embraces measurements of borehole deviation, ground water flow, undisturbed ground temperature profile, secondary fluid and groundwater temperature variations in time, theoretical analyses with a FEM software, Distributed Thermal Response Test (DTRT), and pressure drop. Significant attention is devoted to distributed temperature measurements using optic fiber cables along the BHEs during heat extraction and heat injection from and to the ground.</p> / QC 20100517 / EFFSYS2 / Efficient Use of Energy Wells for Heat Pumps