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Hemmingway, Phil
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Hemmingway, Phil
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Hemmingway, Phil
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- PublicationDesign and development of a low-cost thermal response rigA thermal response test (TRT) is a controlled insitu test during which a known quantity of heat energy is injected into a closed loop heat-exchanger pipe while the heat dissipation rate into the surrounding ground is monitored. Results from a test can be interpreted to determine a number of ground thermal parameters with are vital design requirements for any medium to large scale ground source energy system. This paper describes the design and construction of a low cost TRT rig and compares the results obtained from a test using the constructed rig and a commercially built rig in order to evaluate the accuracy of the constructed equipment. The TRT rig is designed in accordance with the following principles: keep construction costs low, improve the cost-efficiency of TRT testing by incorporating remote data transmission capability and ensure attainment of sufficient accuracy to satisfy the design requirements of ground source energy systems. Analysis of data collected by the TRT rigs result in a calculated thermal conductivity of 1.9 W/mK in both cases. This value falls within the range expected for the tested geological formation and confirms the accuracy of both test rigs.
2066Scopus© Citations 5 - PublicationGeothermal energy : settlement and water chemistry in Cork, IrelandDetailed analysis of potential water chemistry and settlement issues associated with the installation of open-loop geothermal systems is infrequently carried out. This has led to the failure of several previously installed systems. Chemical analysis of water extracted from beneath the Cork docklands, Ireland has been performed by the authors in order to assess the suitability of the area for the exploitation of open-loop geothermal energy. The possibility of settlement induced by pumping of groundwater for open-loop systems has also been examined. Current market penetration of ground source heat pumps in Ireland is discussed to illustrate the infancy of the technology in Ireland relative to other European countries and to highlight the necessity of approaching the possible installation of such systems with the care required. Water extracted from beneath the docklands shows that significant water chemistry issues exist. Laboratory and field tests confirm that optimal concentration levels of several water chemistry characteristics are significantly exceeded; leading to the conclusion that open-loop exploitation in the area may not be suitable. In addition, settlement induced by pumping of water could potentially lead to a consolidation settlement in excess of 30 mm due primarily to the existence of highly compressible alluvium.
1478Scopus© Citations 6 - PublicationThermal response testing of compromised borehole heat exchangersThe results of five thermal response tests (TRTs) are presented. Three of the tests were carried out consecutively on the same borehole to illustrate the importance of allowing artificially imposed thermal gradients to dissipate prior to commencement or re-commencement of a test following testing issues. The two remaining tests carried out on separate boreholes confirm the results obtained by the first(uncompromised) of the initial three tests. The testing regime demonstrates the necessity of careful performance of TRT’s and shows the variation in costs/required borehole length which may occur if testing problems occur on site.
611Scopus© Citations 3 - PublicationEnergy piles: site investigation and analysisDespite an increasing worldwide use of geothermal energy foundations, there is a lack of published guidelines and results from thermal response testing of such installations. In this paper the results are presented from thermal response, thermal recovery and laboratory thermal testing performed at two sites in Ireland. Some practical issues concerned with the use of thermal response testing rigs, designed for use with deep boreholes, on relatively short piles are discussed and addressed. Given the relatively short geothermally active depth of the energy foundations tested, and the fact that the University College Dublin thermal response testing rig has been designed primarily for testing on medium and deep geothermal boreholes, thermal response tests of shorter durations than are normally used for deep boreholes were performed. The techniques used to analyse the various test results are outlined, and the resulting values of thermal conductivity obtained are within the range of those expected for the prevailing geology of the sites.
1320Scopus© Citations 16 - PublicationDesign and development of a low-cost divided bar apparatusA divided bar apparatus is deemed to be the most accurate method of measuring the thermal conductivity, λ, (W/mK) of intact rock cores in the laboratory. The divided bar is a steady-state comparative method in which the temperature drop across a disk of rock is compared with that across a disk of standard material of known conductivity. Thermal conductivity test results obtained from rock cores can be used in software programs to determine the design requirements for any medium to large-scale ground-source energy system. This paper describes the design and development of a low-cost divided bar apparatus and compares the values obtained to those achieved by previous researchers and those recommended by EED, a commonly used borehole heat exchanger design software program. The divided bar was designed in accordance with the following principles: keep construction costs low by using readily available materials, develop a simplistic operating procedure to promote continuity of use and cater for the testing of different sized rock cores. As there are currently no recognised testing standards available for operation of a divided bar apparatus, the sample preparation procedure for samples tested on the UCD divided bar apparatus was developed as a proposed standard testing procedure. The proposed procedure amalgamates the developments and suggestions of previous researchers in addition to published test procedures in Ulusay and Hudson (2007), and could possibly contribute towards the development of a standardised procedure for testing on a divided bar apparatus. The test results presented in this paper demonstrate a strong relationship between thermal conductivity and mineral composition with the effects of porosity also having a notable influence on the thermal conductivity of the tested rocks.
920Scopus© Citations 8