Characterization of the Effects of Borehole Configuration and Interference with Long Term Ground Temperature Modelling of Ground Source Heat Pumps

Heating And Cooling ◽

Ground source heat pumps (GSHPs) are an environmentally friendly alternative to conventional heating and cooling systems because of their high efficiency and low greenhouse gas emissions. The ground acts as a heat sink/source for the excess/required heat inside a building for cooling and heating modes, respectively. However, imbalance in heating and cooling needs can change ground temperature over the operating duration. This increase/decrease in ground temperature lowers system efficiency and causes the ground to foul—failing to accept or provide more heat. In order to ensure that GSHPs can operate to their designed conditions, thermal modelling is required to simulate the ground temperature during system operation. In addition, the borehole field layout can have a major impact on ground temperature. In this study, four buildings were studied—a hospital, fast-food restaurant, residence, and school, each with varying borehole configurations. Boreholes were modeled in a soil volume using finite-element methods and heating and cooling fluxes were applied to the borehole walls to simulate the GSHP operation. 20 years of operation were modelled for each building for 2x2, 4x4, and 2x8 borehole configurations. Results indicate that the borehole separation distance of 6 m, recommended by ASHRAE, is not always sufficient to prevent borehole thermal interactions. Benefits of using a 2x8 configuration as opposed to a 4x4 configuration, which can be observed because of the larger perimeter it provides for heat to dissipate to surrounding soil were quantified. This study indicates that it is important to carefully consider ground temperature during the operation of a GSHP. Borehole separation distances, layout, and hybridization should be studied to alleviate ground fouling problems.

Characterization of the effects of borehole configuration and interference with long term ground temperature modelling of ground source heat pumps

Applied Energy ◽

10.1016/j.apenergy.2016.07.048 ◽

2016 ◽

Vol 179 ◽

pp. 1032-1047 ◽

Cited By ~ 24

Author(s):

Ying Lam E. Law ◽

Seth B. Dworkin

Keyword(s):

Heat Pumps ◽

Ground Temperature ◽

Characterization of the Effects of Borehole Layouts in Geo-exchange

10.32920/ryerson.14662473.v1 ◽

2021 ◽

Author(s):

Ying Lam Law

Keyword(s):

Separation Distance ◽

Ground Temperature ◽

Ground Temperatures ◽

Heating And Cooling ◽

Aspect Ratios ◽

Ground Source ◽

Thermal Imbalance ◽

Cooling Loads

In a ground-source heat pump (GSHP) system, when the heating and cooling loads are not balanced, the ground temperature may migrate up or down after a few years of operation. This change in ground temperature can lower system efficiency because of the ineffective heat transfer temperatures. The present work contributes to fundamental understanding of thermal imbalance in borehole design. Long term ground temperatures were simulated using finite element methods to imitate the performance of GSHP systems. Borehole field configurations are explored and different aspect ratios of borehole layouts were compared. In addition, an alternative borehole configuration was studied, which involves alternating the length of individual boreholes within a single system. The results of the studies expressed potential in alleviating the effects of thermal imbalance by changing borehole field layout and potential in reducing borehole separation distance by altering individual borehole lengths.

Characterization of the Effects of Borehole Layouts in Geo-exchange

10.32920/ryerson.14662473 ◽

2021 ◽

Author(s):

Ying Lam Law

Keyword(s):

Separation Distance ◽

Ground Temperature ◽

Ground Temperatures ◽

Heating And Cooling ◽

Aspect Ratios ◽

Ground Source ◽

Thermal Imbalance ◽

Cooling Loads

In a ground-source heat pump (GSHP) system, when the heating and cooling loads are not balanced, the ground temperature may migrate up or down after a few years of operation. This change in ground temperature can lower system efficiency because of the ineffective heat transfer temperatures. The present work contributes to fundamental understanding of thermal imbalance in borehole design. Long term ground temperatures were simulated using finite element methods to imitate the performance of GSHP systems. Borehole field configurations are explored and different aspect ratios of borehole layouts were compared. In addition, an alternative borehole configuration was studied, which involves alternating the length of individual boreholes within a single system. The results of the studies expressed potential in alleviating the effects of thermal imbalance by changing borehole field layout and potential in reducing borehole separation distance by altering individual borehole lengths.

Development of design guidelines for thermo-active foundations

Indoor and Built Environment ◽

10.1177/1420326x17690018 ◽

2017 ◽

Vol 27 (6) ◽

pp. 805-817 ◽

Cited By ~ 2

Author(s):

Byung C. Kwag ◽

Moncef Krarti

Keyword(s):

Heat Pump ◽

Heat Pumps ◽

Design Guidelines ◽

Conventional Heating ◽

Ground Source Heat Pump ◽

External Energy ◽

Geothermal Heat ◽

Heating And Cooling ◽

Ground medium can be utilized as a direct energy source to heat and cool buildings. In particular, ground source heat pump systems take advantage of the year-round mild deep earth temperature without a significant reliance on any external energy sources. However, the high installation cost of ground source heat pumps associated with high drilling cost of vertical boreholes often make these systems less cost-effective compared to conventional heating and cooling systems. Thermo-active foundations can be a viable solution to reduce ground source heat pump high installation costs by embedding heat exchangers within building foundation structures. Compared to ground source heat pumps, only limited analyses and research studies have been reported for thermo-active foundations especially for the US climates. In particular, no specific design guidelines have been reported for thermo-active foundations especially for US climates. In this paper, a simplified design approach was developed and applied for specifying geothermal heat pump size and heat exchanger loop length to meet all or part of building heat and cooling thermal loads. The developed guidelines would thus provide a proper design guide for installation of thermo-active foundations for heating and cooling of both US residential and commercial buildings.

Application and development of ground source heat pump technology in China

Protection and Control of Modern Power Systems ◽

10.1186/s41601-021-00195-x ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Chaofan Song ◽

Yang Li ◽

Taha Rajeh ◽

Ling Ma ◽

Jun Zhao ◽

...

Keyword(s):

High Efficiency ◽

Heat Pumps ◽

Economic Feasibility ◽

Renewable Energy Technologies ◽

Development History ◽

Energy Technologies ◽

Heating And Cooling ◽

Ground Source ◽

Promising Development

AbstractGround source heat pumps (GSHPs) are one of the renewable energy technologies with features of high efficiency, energy saving, economic feasibility and environmental protection. In China, GSHPs have been widely used for building heating and cooling in recent years, and have shown great potential for future energy development. This paper summarizes the classification, development history, and use status of shallow GSHPs. Several typical engineering cases of GSHP technology are also specified and analyzed. Finally, promising development trends and some advanced technologies are illustrated.

Ground Source Heat Pumps: Considerations for Large Facilities in Massachusetts

10.31224/osf.io/mh4py ◽

2020 ◽

Author(s):

Eric Wagner ◽

Benjamin McDaniel ◽

Dragoljub Kosanovic

Keyword(s):

Co2 Emissions ◽

Current System ◽

Cost Benefit ◽

Heating System ◽

Heat Pumps ◽

Heating And Cooling ◽

Ground Source ◽

Industry Standards ◽

Conventional Cooling

Ground-source heat pump (GSHP) systems have been implemented at large scales on several university campuses to provide heating and cooling. In this study, we test the idea that a GSHP system, as a replacement for an existing Combined Heat and Power (CHP) heating system coupled with conventional cooling systems, could reduce CO2 emissions, and provide a cost benefit to a university campus. We use the existing recorded annual heating and cooling loads supplied by the current system and an established technique of modeling the heat pumps and borehole heat exchangers (BHEs) using a TRNSYS model. The GSHP system is modeled to follow the parameters of industry standards and sized to provide an optimal balance of capital and operating costs. Results show that despite a decrease in heating and cooling energy usage and CO2 emissions are achieved, a significant increase in electric demand and purchased electricity result in an overall cost increase. These results highlight the need for thermal energy storage, onsite distributed energy resources and/or demand response in cases where electric heat pumps are used to help mitigate electric demand during peak periods.

An Analytical Optimization Algorithm for Wind Energy Coupled GSHP Systems for Sustainable Building HVAC

Advanced Energy Systems ◽

10.1115/imece2003-55397 ◽

2003 ◽

Cited By ~ 2

Author(s):

Birol I. Kilkis

Keyword(s):

Optimization Algorithm ◽

Alternative Energy ◽

Cost Effective ◽

Heat Pumps ◽

Energy Resources ◽

Sustainable Building ◽

Combined Application ◽

Heating And Cooling ◽

Effective utilization of low-enthalpy energy resources in heating, ventilating, and air-conditioning (HVAC) of sustainable buildings require a careful optimization to assure the most economical coupling of HVAC systems with low-enthalpy energy resources. In one of the two separate prior studies an optimization algorithm for the optimal coupling of heat pumps and radiant panel heating and cooling systems was developed. In the second prior study an optimization algorithm for driving ground source heat pumps with wind turbines was developed. In this study these two algorithms were combined for a compound utilization of alternative energy resources. This paper describes the optimization algorithms, emphasizes their importance in achieving a cost effective combined application, and discusses the results obtained from the examples given.

A European Database of Building Energy Profiles to Support the Design of Ground Source Heat Pumps

Energies ◽

10.3390/en12132496 ◽

2019 ◽

Vol 12 (13) ◽

pp. 2496 ◽

Cited By ~ 7

Author(s):

Laura Carnieletto ◽

Borja Badenes ◽

Marco Belliardi ◽

Adriana Bernardi ◽

Samantha Graci ◽

...

Keyword(s):

Heat Pump ◽

Energy Demand ◽

Residential Buildings ◽

Building Energy ◽

Heat Pumps ◽

Climatic Conditions ◽

Heating And Cooling ◽

Energy Profiles ◽

The design of ground source heat pumps is a fundamental step to ensure the high energy efficiency of heat pump systems throughout their operating years. To enhance the diffusion of ground source heat pump systems, two different tools are developed in the H2020 research project named, “Cheap GSHPs”: A design tool and a decision support system. In both cases, the energy demand of the buildings may not be calculated by the user. The main input data, to evaluate the size of the borehole heat exchangers, is the building energy demand. This paper presents a methodology to correlate energy demand, building typologies, and climatic conditions for different types of residential buildings. Rather than envelope properties, three insulation levels have been considered in different climatic conditions to set up a database of energy profiles. Analyzing European climatic test reference years, 23 locations have been considered. For each location, the overall energy and the mean hourly monthly energy profiles for heating and cooling have been calculated. Pre-calculated profiles are needed to size generation systems and, in particular, ground source heat pumps. For this reason, correlations based on the degree days for heating and cooling demand have been found in order to generalize the results for different buildings. These correlations depend on the Köppen–Geiger climate scale.

Clean Energy for Cooling and Heating with Ground Source Heat Pumps

Advances in Nanoscience and Nanotechnology ◽

10.33140/ann.03.02.5 ◽

2019 ◽

Vol 3 (2) ◽

Keyword(s):

Renewable Energy ◽

Alternative Energy ◽

Renewable Energy Sources ◽

Clean Energy ◽

Heat Pumps ◽

Hot Water ◽

Energy Sources ◽

Heating And Cooling ◽

In the recent attempts to stimulate alternative energy sources for heating and cooling of buildings, emphasise has been put on utilisation of the ambient energy from ground source heat pump systems (GSHPs) and other renewable energy sources. Exploitation of renewable energy sources and particularly ground heat in buildings can significantly contribute towards reducing dependency on fossil fuels. The study was carried out at the Energy Research Institute (ERI), between September 2016 and November 2017. This paper highlights the potential energy saving that could be achieved through use of ground energy source. The main concept of this technology is that it uses the lower temperature of the ground (approximately <32°C), which remains relatively stable throughout the year, to provide space heating, cooling and domestic hot water inside the building area. The purpose of this study, however, is to examine the means of reducing of energy consumption in buildings, identifying GSHPs as an environmental friendly technology able to provide efficient utilisation of energy in the buildings sector, promoting the use of GSHPs applications as an optimum means of heating and cooling, and presenting typical applications and recent advances of the DX GSHPs. It is concluded that the direct expansion of GSHP are extendable to more comprehensive applications combined with the ground heat exchanger in foundation piles and the seasonal thermal energy storage from solar thermal collectors. This study highlights the energy problem and the possible saving that can be achieved through the use of the GSHP systems. This article discusses the principle of the ground source energy, varieties of GSHPs, and various developments.