Thermal Response Testing: Results and Experiences from a Ground Source Heat Pump Test Facility with Multiple Boreholes

This paper presents a summary of the results of various thermal response tests performed on nine adjacent 80-m-deep boreholes. Over forty tests with durations between 48 and 320 hours have been performed during the last 3 years. All nine boreholes were tested under similar conditions to check random uncertainties between tests. Several tests with diverse conditions were then performed to study sensitivity of test results to test variables and to quantify uncertainty in test results. Some of the tests were also repeated to ascertain reproducibility of the results. The paper also presents experimental measurements of borehole annulus temperatures during a test and recovery times of boreholes after a test

An Analytical Method to Calculate Borehole Fluid Temperatures for Time-scales from Minutes to Decades

Knowledge of borehole exit fluid temperature is required to optimize the design and performance of ground source heat pump systems. The borehole exit fluid temperature depends upon the prescribed heat injection and extraction rates. This paper presents a method to determine the fluid temperature of a single or a multiple borehole heat exchanger for any prescribed heat injection or extraction rate. The fluid temperature, from minutes to decades, is determined using step response functions. An analytical radial solution is used for shorter times. A finite line-source solution is used for longer times. The line-source response function has been reduced to one integral only. The derivative, the weighting function, is given by an explicit formula both for single boreholes and any configuration of vertical boreholes

Life-Cycle Cost-Optimized Cooling Systems for European Office Buildings

This study compares the life-cycle costs of various conventional and emerging cooling systems in representative European climates and energy markets. Firstly, cooling demands and energy requirements of a multi-story office building are determined in compliance with local building codes in six different European locations. Life-cycle costs of various cooling systems are then calculated using location-specific market prices and economic data. The results indicate that no single cooling system is an optimal choice for all locations. In cold climates, conventional vapour compression systems are shown to have the lowest life-cycle costs. In moderate and warm climates, solar electricity driven vapour compression systems have the lowest life-cycle costs. Absorption and solar thermal cooling systems are shown to be economically infeasible under current market conditions

Thermal modelling and evaluation of borehole heat transfer.

The use of ground source heat pump systems to provide heating and cooling in buildings has increased greatly in the last decade or so. These systems have a high potential for energy efficiency, which has environmental and economic advantages. Moreover, the energy efficiency of the ground source heat pump systems can be further enhanced by optimizing the performance of the system. However, a key obstacle to the performance optimization of ground source heat pump systems is the scarcity of mathematical models that can rapidly, yet accurately, simulate the dynamic thermal response of the borehole system. This study aims to develop analytical models and methods that can simulate the thermal response of a borehole system in time scales from minutes to years. An analytical solution to model the short-time response of the borehole system is presented. The solution studies the heat transfer problem in the Laplace domain and provides an exact solution to the radial heat transfer problem in the borehole. A finite-length line-source solution to determine the long-term response of the borehole system is also presented. The line-source solution can be used for modelling both single and multiple borehole systems. The analytical and finitelength line-source solutions were combined to obtain step-response functions for various configurations of borehole systems. The step-response functions are valid from short (hours) to long (years) periods. A load aggregation method is also presented to speed up the simulations of the borehole systems. All the proposed models and methods can be easily implemented in any building energy simulation software to optimize the overall performance of ground source heat pump systems. The study also analyzes various aspects of the thermal response testing and evaluation of borehole systems. A ground source heat pump test facility with nine boreholes was used for the experimental investigations. Several thermal response tests were conducted for issues that include random variations between tests, sensitivity of system design to uncertainties in test results, convective heat transport in boreholes, and recovery times after a test. The evaluations of multiinjection rate tests on groundwater-filled boreholes were also extensively studied. Recommendations regarding each of these issues are suggested to improve the testing and evaluation procedure of borehole systems

Testing and Validation of TEKNOsim: A Building Energy Simulation Program.

TEKNOsim is a well-established software tool for simulation of thermal indoor climate. It is used for modelling and simulation of thermal loads, indoor temperatures and thermal comfort. TEKNOsim 5, a new version of the simulation tool has been launched with several new features and enhanced functionalities. This paper presents results of testing and validation of TEKNOsim 5 against two state-of-the-art building energy simulation tools, IDA-ICE and DesignBuilder. Comparisons with the reference tools have been made for a number of test cases. Simulation results indicate that, for realistic scenarios, there exists a very close agreement between TEKNOsim and the reference tools. The largest discrepancies between the simulation tools are observed for unrealistic scenarios. Besides this, the observed trends in discrepancies between the tools also suggest that the algorithms used in TEKNOsim 5 are correct

Long-term performance measurement and analysis of a small-scale ground source heat pump system

Recent data suggest that heat pumps, despite having the potential to cover over 90% of the global space and water heating demands, only provide less than 5% of global heating. Heat pumps, in general, and ground source heat pumps, specifically, offer significant potential for energy savings and carbon emissions reduction in buildings. The realization of these potential benefits, however, requires proper design, installation, and operation of the entire heat pump system. This paper presents the performance analysis of a Swedish ground source heat pump system providing space heating and hot water to a sports clubhouse. The installation has been carefully instrumented to enable full characterization of the whole system including auxiliary components such as circulation pumps and supplementary heating. Seasonal performance factors, calculated for monthly and annual periods using high-quality, high-resolution measurement data collected over three years of system operation, have been reported based on the SEPEMO (SEasonal PErformance factor and MOnitoring for heat pump systems) and Annex 52 boundary schemes for evaluating and benchmarking the performance of the ground source heat pump system. The auxiliary system components were shown to have a large impact on the overall performance of the system. In particular, the legionella protection system was found to affect performance considerably. Recommendations as to how to improve the performance of the system under study and other similar systems are made from the design, installation, and operation perspectives

Calculation Tool for Effective Borehole Thermal Resistance

This paper presents a tool for computing thermal resistance of single U-tube ground heat exchangers placed in vertical boreholes. The tool is complete in the sense that it can compute both local and effective thermal resistances for either grouted or groundwater-filled boreholes. For grouted boreholes, it utilizes the highly accurate multipole method. For groundwater-filled boreholes, it utilizes recently-published convection correlations. Thermal property routines for water and water-antifreeze mixtures allow calculation of the interior convective thermal resistance for a wide range of cases

Association patterns of volatile metabolites in urinary excretions among Type-2 Non-Insulin dependent diabetes patients

Background: Patterns of volatile metabolites in urine are important to detect abnormalities associated with diabetes. Present study was conducted to find out the excretion patterns of endogenously produced alcohols in urine for type 2 (Non-Insulin Dependent) diabetes mellitus. A cross sectional analytical study was conducted with duration extended from Jan to Mar 2015.Methods: The current study included 40 patients with chronic type 2 diabetes mellitus. In total, 10 sex and age matched subjects with no history of any disease were considered as controls. Blood sugar was estimated by autoanalyzer using standard kit of Merck following manufacturer`s instructions. Urine sugar was quantitatively detected by biuret reagent using titration technique. Urinary alcohol was identified and estimated by gas chromatography.  Urinary ketone bodies were estimated by urinary strip.Results: It was observed that level of fasting blood sugar was significantly increased (P<0.001) in patients as compared to their controls. The blood sugar and urinary alcohol in patients were 3.0% and 6.0% respectively. Urinary ketone bodies were found to be 2+. On the other hand urine sugar, alcohol and ketone bodies were not detected in the negative control subjects.Conclusions: It is concluded that urinary alcohol is endogenously produced in patients with type 2 diabetes due to uncontrolled hyperglycemia. However further work is needed to find out the ratio of urinary and blood alcohol which may confirm the present findings

Second-order multipole formulas for thermal resistance of single U-tube borehole heat exchangers

The borehole thermal resistance is both an important design parameter and a key performance characteristic of a borehole heat exchanger. Another quantity that is particularly important for deep borehole heat exchangers is the internal thermal resistance between the upward-flowing and downward-flowing fluid channels in the borehole. The multipole method is a well-known and robust method to compute both these thermal resistances. However, it has a fairly intricate mathematical algorithm and is thus not trivial to implement. Consequently, there is considerable interest in developing explicit multipole formulas. So far zeroth-order and first-order multipole formulas have been derived for cases where the two legs of the borehole are placed symmetrically in a borehole. This paper presents new explicit second-order multipole formulas, which provide significant accuracy improvements over the previous formulas

Impact of Training on Expectation of Employee and Employer: A comparative study

Organizations today spend millions of dollars on training to enhance the performance of their employees, which leads to formation of expectation on employers end as well as employees ends observing this phenomena ,this research was conducted to analyze the expectations of employee and employer and its impact on post training satisfaction, for that matter data was collected from 20 organization where training is provided ,sample size was 20 training / HR managers and per managers 5 employees, paired sample t test was applied to gauge the difference or similarity between the perception and expectation of employees and employer, after the analysis it was found that there is significant difference between the perception of employee and employers on the expected training outcomes and no similarity existed between the expectation of employee and employer which did not have positive effect on post training satisfaction