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

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

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%

The Importance of Heat Pump COP in the Economics of 5th Generation District Heating and Cooling Networks

This paper describes the investigation of heat pumps for GreenSCIES, a 5th Generation heat network in Islington, London. The paper describes the GreenSCIES concept integrating Mobility, Power and Heat into a local energy system. At the heart of the system is a 5th generation heat network, which utilises an ambient heat network to capture secondary heat and share heat between different applications. The GreenSCIES network, technology utilised and buildings connected are described. Heat pumps are used to amplify the temperature of the ambient loop to deliver heat at the required temperature in connected buildings. A number of different heat pumps using different refrigerants and configurations were appraised in this study. This considered the performance, safety, environmental impact, operational and capital expenditure point of view. The study shows the importance of heat pump COP on the economics of operating the system and suggests innovative series arrangements in order to improve performance and economics

Waste heat recovery from urban electrical cable tunnels

Electrical power distribution within cities is most often distributed through underground cables located just below the road surface. Due to steadily increasing electricity demands, many power suppliers are making large investments in housing these cables in underground tunnels. These urban cable tunnels often extend to many kilometres in length. Through the electrical loading of the cables a significant amount of heat is generated. Often this heat has to be removed through ventilation in order to avoid overheating the cables and to provide safe conditions for access. As opposed to rejecting the heat to the atmosphere, this low grade energy could potentially be recovered, upgraded if necessary, and distributed to nearby heat users above ground. This paper discusses possible heat recovery methods applicable for urban electricity distribution networks, i.e. transformers and cable tunnels. It also presents results from a modelling-based preliminary feasibility study which used cable tunnels in London as a case study

Bacterial Protein Structures Reveal Phylum Dependent Divergence

Protein sequence space is vast compared to protein fold space. This raises important questions about how structures adapt to evolutionary changes in protein sequences. A growing trend is to regard protein fold space as a continuum rather than a series of discrete structures. From this perspective, homologous protein structures within the same functional classification should reveal a constant rate of structural drift relative to sequence changes. The clusters of orthologous groups (COG) classification system was used to annotate homologous bacterial protein structures in the Protein Data Bank (PDB). The structures and sequences of proteins within each COG were compared against each other to establish their relatedness. As expected, the analysis demonstrates a sharp structural divergence between the bacterial phyla Firmicutes and Proteobacteria. Additionally, each COG had a distinct sequence/structure relationship, indicating that different evolutionary pressures affect the degree of structural divergence. However, our analysis also shows the relative drift rate between sequence identity and structure divergence remains constant