Modelling Of The Thermal Interactions Of Underground Railways With Nearby Vertical Ground Heat Exchangers In An Urban Environment

Ground source heat pumps (GSHPs) can provide an efficient way of heating and cooling buildings due to their high operating efficiencies. The implementation of these systems in urban environments could have further benefits. In such locations ground source heat is potentially available from alternative sources such as underground railways (URs). The potential benefits for using the waste heat generated by URs with localised GSHPs are established in this thesis. This was achieved through investigations of UR-GSHP interactions. The research detailed here was mainly conducted through Finite Element (FE) numerical modelling and analysis. First a preliminary two-dimensional (2D) FE model was developed. This model was highly simplified to enable rapid analysis of the systems. The model was used to establish key parameters and phenomena for more detailed additional research. Since the operation of the URs and GSHP involves complex, transient, three-dimensional (3D) transport phenomena and extreme geometrical aspect ratios, 3D numerical models of URs and vertical ground heat exchangers (GHEs) were independently developed and validated. These individual models were then built into the same modelling environment for their combined analysis. Initial investigations with the combined 3D model showed that interactions occur between URs and localised GSHPs. In order to investigate the effect of specific parameter variations on the earlier established UR-GSHP interactions, a parametric analysis was conducted. The analysis included two sets of studies. The first group of studies considered different geometrical arrangements of the systems, and the second group investigated the effect of altered operational characteristics options on the interactions. Overall the results suggested that the performance of a GSHP can be significantly improved if the GHE array is installed near to the UR tunnel. It was shown that the improvement on the GHEs average heat extraction rate due to the heat load from the UR tunnel can be high as ~ 40%, depending on the size and shape of the GHE array and its proximity to the UR tunnel(s). It was also concluded that if the design aim is to enhance the heat extraction rates of urban GSHP systems, constructing the GHEs as close as possible to the UR tunnel would be essential. The results gathered from the parametric analysis were used to develop a formula. This formula is one of the key contributions to knowledge from this research. The formula developed allows approximating the GHEs’ heat extraction improvements due to the nearby tunnel(s) heat load(s). The formula makes use of a single variable named as interaction proximity. This variable was found to be one of the key parameters impacting on UR-GSHP interactions. At the end of the thesis, conclusions are drawn concerning the thermal interactions of URs with nearby vertical GHEs and the numerical modelling of such systems. Recommendations for further research in this field are also suggested

Modelling Of The Thermal Interactions Of Underground Railways With Nearby Vertical Ground Heat Exchangers In An Urban Environment

Ground source heat pumps (GSHPs) can provide an efficient way of heating and cooling buildings due to their high operating efficiencies. The implementation of these systems in urban environments could have further benefits. In such locations ground source heat is potentially available from alternative sources such as underground railways (URs). The potential benefits for using the waste heat generated by URs with localised GSHPs are established in this thesis. This was achieved through investigations of UR-GSHP interactions. The research detailed here was mainly conducted through Finite Element (FE) numerical modelling and analysis. First a preliminary two-dimensional (2D) FE model was developed. This model was highly simplified to enable rapid analysis of the systems. The model was used to establish key parameters and phenomena for more detailed additional research. Since the operation of the URs and GSHP involves complex, transient, three-dimensional (3D) transport phenomena and extreme geometrical aspect ratios, 3D numerical models of URs and vertical ground heat exchangers (GHEs) were independently developed and validated. These individual models were then built into the same modelling environment for their combined analysis. Initial investigations with the combined 3D model showed that interactions occur between URs and localised GSHPs. In order to investigate the effect of specific parameter variations on the earlier established UR-GSHP interactions, a parametric analysis was conducted. The analysis included two sets of studies. The first group of studies considered different geometrical arrangements of the systems, and the second group investigated the effect of altered operational characteristics options on the interactions. Overall the results suggested that the performance of a GSHP can be significantly improved if the GHE array is installed near to the UR tunnel. It was shown that the improvement on the GHEs average heat extraction rate due to the heat load from the UR tunnel can be high as ~ 40%, depending on the size and shape of the GHE array and its proximity to the UR tunnel(s). It was also concluded that if the design aim is to enhance the heat extraction rates of urban GSHP systems, constructing the GHEs as close as possible to the UR tunnel would be essential. The results gathered from the parametric analysis were used to develop a formula. This formula is one of the key contributions to knowledge from this research. The formula developed allows approximating the GHEs’ heat extraction improvements due to the nearby tunnel(s) heat load(s). The formula makes use of a single variable named as interaction proximity. This variable was found to be one of the key parameters impacting on UR-GSHP interactions. At the end of the thesis, conclusions are drawn concerning the thermal interactions of URs with nearby vertical GHEs and the numerical modelling of such systems. Recommendations for further research in this field are also suggested

Promoting grammatical development through captions and textual enhancement in multimodal input-based tasks

This study assessed the extent to which captions, textually unenhanced and enhanced, can draw learners’ attention to and promote the acquisition of a second language (L2) grammatical construction. A pretest–posttest–delayed posttest experimental design was employed. Seventy-two Korean learners of English were randomly assigned to an enhanced captions group, an unenhanced captions group, and a no captions group. Each group completed a series of treatment tasks, during which they watched news clips under their respective captioning condition. The target L2 construction was the use of the present perfect versus the past simple in reporting news. For the enhanced captions group, the present perfect and past simple forms were typographically enhanced using a different color. Eye-movement indices were obtained to examine attentional allocation during the treatment, and oral and written productive tests and a fill-in-the-blank test were used to assess participants’ gains. A series of mixed-effects models found both captioning and textual enhancement effective in drawing learners’ attention to and facilitating development in the use of the target construction. In addition, positive links were identified between attention to captions and learners’ gains

Project SHOES: Secondary heat opportunities from electrical substations

Through the mechanism of stepping up and stepping down voltages with electrical power transformers, losses in the form of heat occur and are dissipated to the atmosphere. These losses have the opportunity to be recovered and upgraded to help support the thermal demands of buildings as allow carbon secondary heat source. The electrification of heat facilitates the uptake of electrically driven heat pumps that are efficient means of upgrading low temperature heat sources to commonly used temperatures and the employment of district heating networks enables the transition of these alternative heat sources into the economy. This paper describes the results discovered from an initial investigation on the contribution available from a transformer energy recovery scheme using the Southampton Bulk Supply Point substation and District Heating Scheme as a case study. Benefits to the heat sector and asset owner are analysed from the results considering the techno-economic, environmental and social performance with the aim to provide guidance to the engineering community for further in-depth feasibility studies on this waste energy recovery concep

Cooling with heat recovery for electrical cable tunnels in cities

Within cities, electrical power is often distributed by means of underground cable tunnels, frequently extending for many kilometres. Cables can generate significant heat, with the quantity of heat being directly related to the electrical load carried. Tunnel air temperatures are generally controlled by ventilation using outside air; preventing the cables from overheating. If active cooling was provided, tunnel air temperatures could be further reduced, permitting higher electrical loadings to be used. Using an air/water heat exchanger to cool the outside air entering the ventilation shaft has been investigated. The temperature of the heat extracted (to water) was increased using a heat pump before transfer to a heat network. Benefits identified included reduction in cable temperatures, and carbon and cost savings compared to conventional heat delivery

Heat Recovery Opportunities from Wastewater Treatment Plants

Wastewater offers the potential of a widespread resource for low-temperature waste heat, with wastewater in sewers normally at temperatures greater than ambient due to the use of hot water in buildings. Heat can be recovered from wastewater from different locations, such as the wastewater pipework within a building, the sewage network or at wastewater treatment plants (WWTPs). The latter represents an interesting alternative as wastewater flow rates are generally much higher in the effluent of treatment plants than in sewers. Additionally, the temperatures may be above ambient, as the biological sewage treatment process results in some heat generation. This paper investigates the potential availability of waste heat from WWTPs across the UK, with a total thermal energy output of 26.2 TWh [89.5 MMDth (US)] per annum being estimated. A possible configuration for recovering waste heat from the WWTP effluent is also presented and used to assess the benefits that could be obtained against conventional heating technologies based on a case study in London. Although the case study is based in the UK, the methodology hereby described can also be applied to evaluate the potential for heat recovery from wastewater treatment plants in other countries

Ambient loop district heating and cooling networks with integrated mobility, power and interseasonal storage

This paper describes a heat pump investigation for GreenSCIES (GS), a fifth Generation district heating and cooling (5DHC) network in Islington, London. The paper describes the GreenSCIES concept integrating Mobility, Power and Heat into a Smart Local Energy System (SLES). At the heart of the system is an ultra-low temperature ambient loop network, which permits bi-directional flow within the pipes to allow energy exchange between heating and cooling customers at different times and in different locations, depending on where demand is at any given time. An existing data centre provides the primary source of waste heat for the scheme. Heat pumps in distributed energy centres are utilised to amplify the temperature of the ambient loop to deliver heat in connected buildings. The energy centres integrate heat pumps with building-mounted solar photovoltaic (PV) systems and electric vehicle (EV) charging points. The paper provides an overview of the integrated SLES concept, focussing on the heat pump selection and the short and long-term thermal storage options designed for the scheme. The results show that even the smaller constructible ‘New River’ scheme will save 5,000 tons of CO2e annually. This will tend to 100% as the grid decarbonise further. Therefore, the GS SLES concept applied to urban areas could deliver significant carbon emission savings in the UK and elsewhere. Practical application: Project GreenSCIES, is a detailed design study to develop a Smart, Local Energy System (SLES) for a large community in the London Borough of Islington. Our consortium have developed an innovative SLES concept, centred around a fifth generation district heating and cooling network. The GS ambient loop systems have negligible losses and much greater efficiencies than traditional district heat networks. As recognised by the UK Government’s Heat and Buildings Strategy, ambient loop systems should be considered where large-scale neighbourhood regeneration occurs. The proposed SLES concept applied to wider urban areas could deliver significant carbon emission savings in the UK

Using Databases and Computational Techniques to Infer the Function of Novel Proteins

The Human Genome Project and similar efforts have resulted in the identification of an abundance of novel proteins. There is a need to expedite the process of assigning function to novel proteins. Nuclear magnetic resonance (NMR) spectroscopy can be used to infer a general biological function for a protein of unknown function by identifying compounds that preferentially bind the protein and comparing these results against proteins with defined structure and function. The Functional NMR screen generates hundreds of data sets and a manual analysis of these data sets is laborious and time- consuming. It is hypothesized that several sub-tasks of the Functional NMR can be automated successfully using an integrated database and data analysis system. Our database system integrates NMR data collection, processing, analysis, and data archiving into a unified user interface. An NMR spectra comparison algorithm is designed and implemented to compare NMR data in the presence and absence of a protein to ascertain if any compound-protein binding occurred

Performance Enhancement of Urban Ground Source Heat Pumps through Interactions with Underground Railway Tunnels

Ground source heat pumps (GSHPs) can provide an efficient way of heating and cooling buildings due to their high operating efficiencies. The implementation of these systems in urban environments could have further benefits. In such locations the ground source heat is potentially more accessible via alternative sources such as through underground railways (URs). This paper investigates to what extent the heat in the soil surrounding an UR tunnel could enhance the operation of urban GSHPs installations. To address this, a numerical investigation was set out which included a parametric study considering a number of geometrical options of the systems. The results showed that heat extraction rates of GSHPs installed near UR tunnels can be significantly improved by up to ~ 43%