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01535 Podhale (South Poland) geothermal district heating system
14 Heat pumps
04/01535 Podhale (South Poland) geothermal district heating system Dlugosz, P. Geothermics, 2003, 32, (4-6), 527-533. The search for geothermal resources in the Podhale Region began in the late 1980s. The Banska IG-1 well, drilled in 1981, served as the starting point for an expansion of those research activities. A geothermal pilot plant was put into operation in 1993. During that same year the company Geotermia Podhalanska (GP) was founded and the pilot project, including the first distribution network for 20 customers, was constructed. After the initial phase of project implementation from 1993 to 1995, during which a pilot plant was constructed and put into operation for demonstration purposes by the Polish Academy for Sciences using the first geothermal doublet (a production well in Banska Nizna and a reinjection well in Bialy Dunajec), and connection of 200 households through a small district heating network, the World Bank got involved in the geothermal district heating project. Since then, significant progress has been made, increasing the overall heat capacity and geothermal output as well as the service area to the City of Zakopane, approx. 14 km from the production wells. In November 2001 the first geothermal heat was delivered to customers in Zakopane.
04•01536 Representative building design and internal load patterns for modelling energy use in residential buildings in Hong Kong Wan, K. S. Y. and Yik, F. H. W. Applied Energy, 2004, 77, (1), 69-85. Based on the data collected in recent surveys, models have been established to represent the energy characteristics of living and dining rooms and bedrooms in typical residential buildings in Hong Kong, in respect of the layout and construction; the density and pattern of occupation; the power intensities and operating patterns of lighting and appliances; and air-conditioner operation patterns. With the help of computer simulation, the impacts of varying these characteristics on the annual space cooling load have been evaluated, which allowed representative internal load patterns for residential units to be defined. These are essential data for predicting energy use in residential buildings, which, in turn, is an indispensable part of studies on ways to assess and minimize energy use in such buildings. This paper presents the building model and the internal load and air-conditioner operation patterns established in the study.
04/01537 Subsystem level fault diagnosis of a building's air-handling unit using general regression neural networks Lee, W.-Y. et al. Applied Energy, 2004, 77, (2), 153-170. This paper describes a scheme for on-line fault detection and diagnosis (FDD) at the subsystem level in an Air-Handling Unit (AHU). The approach consists of process estimation, residual generation, and fault detection and diagnosis. Residuals are generated using general regression neural-network (GRNN) models. The G R N N is a regression technique and uses a memory-based feed forward network to produce estimates of continuous variables. The main advantage of a G R N N is that no mathematical model is needed to estimate the system. Also, the inherent parallel structure of the GRNN algorithm makes it attractive for real-time fault detection and diagnosis. Several abrupt and performance degradation faults were considered. Because performance degradations are difficult to introduce artificially in real or experimental systems, simulation data are used to evaluate the method. The simulation results show that the GRNN models are accurate and reliable estimators of highly non-linear and complex A H U processes, and demonstrate the effectiveness of the proposed method for detecting and diagnosing faults in an AHU.
04/01538
The use of downhole heat exchangers Lund, J. W. Geothermics, 2003, 32, (4-6), 535-543. The downhole heat exchanger (DHE), used extensively in Klamath Falls, Oregon, in over 500 installations, and in Turkey and New Zealand, provides heating for one or more homes, schools, and apartment buildings from a single geothermal well. The D H E eliminates the problem of disposal of geothermal fluid, since only heat is extracted from the well. The heat exchangers consist of a loop of pipes or tubes suspended in the geothermal well, through which 'clean' secondary water is pumped or allowed to circulate by natural convection. The maximum output of large installations is typically less than 3 GJ/h or 0.8 MWt, with well depths up to about 150 m, and may be economical under certain conditions at a well depth of 500 m. However, the typical output for an individual home in Klamath Falls tends to be less than 265 MJ/h (0.07 MWt). In order to obtain maximum output, the well must be designed to have an open annulus between the wellbore and casing, with perforations near the top and bottom of the submerged heat exchanger, just below the water surface and at the hot aquifer at the bottom of the well. Natural convection circulates the well water down inside the casing, through the lower perforations, up through the annulus and back into the casing through the upper perforations, with the new geothermal water mixing with the old. This vertical convection cell exposes the D H E to the near-
maximum temperature of the well water and thus increases the heat output of the DHE. The heat output from a D H E system is dependent on the bore diameter, casing diameter, D H E length, tube diameter, number of loops in the well, flow rate and temperature of the geothermal fluid. Based on local experience in Klamath Falls, the 'ruleof-thumb' is that contractors estimate approximately '1 foot of D H E pipe per 1500 Btu/h' (5200 kJ/h/m or 1.44 kW/m) as an average output.
04/01539 Using small reverse cycle air conditioners in relocatable classrooms - a case study Fuller, R. J. and Luther, M. B. Energy and Buildings, 2003, 35, (6), 619629. A 9-month study of four relocatable school buildings, each retro-fitted with small reverse cycle air conditioners (ACs), was conducted to investigate their effectiveness in heating and cooling the classrooms. A comparison with data from previous studies found the energy used by the ACs for heating these temporary classrooms was only 19-20% of the energy used by individual gas heaters installed in permanent classrooms. When equipment efficiencies were considered, the AC units supplied 20-27% less energy to heat the classrooms. The possible reasons for this reduction in supplied energy are explored in this paper. CO2 emissions for the AC units in heating mode, however, were calculated to be 16% greater than for individual gas heaters. The AC units were also used for cooling and on an average the total annual energy consumption for heating and cooling was found to be 11.6 kWh m -z. Responses to a small survey of staff and students about the use and operation of the conditioners are presented. Their responses were more favourable than the predictions of comfort levels in the classrooms using the Predicted Mean Vote-Predicted Percentage of Dissatisfaction (PMV-PPD) model, which indicated 'uncomfortable' conditions on average summer days at 3:00 p.m. and average winter days at 10:00 a.m. Background noise levels in the classrooms with the air conditioners in use were above the recommended maximum design level of 45 dB(A); levels of up to 65 dB(A) were measured.
14
HEAT P U M P S
04/01540 Characteristics of an improved heat-pump cycle for cold regions Ma, G. and Chai, Q. Applied Energy, 2004, 77, (3), 235-247. To increase the heating capacity of air-source heat-pump in cold regions, an improved heat pump cycle with scroll compressor economizer was developed. The measured results of the prototype demonstrate that it can provide a high temperature and high-capacity water supply even under a low ambient temperature of - 1 0 ~ - 1 5 ° C . The performances of the improved heat-pump cycle are comprehensively analysed with aid of the proposed thermodynamic model in this paper. The design parameters and the components of the cycle are optimized and the predicted results. The predicted results discussed indicate that the improved heat pump has high efficiency under all weather conditions and that this improvement is conducive to enlarging the running region of the heat pump and providing an alternative heating service for cold regions.
04/01541 Current status of ground source heat pumps and underground thermal energy storage in Europe Sanner, B. et al. Geothermies, 2003, 32, (4-6), 579-588. Geothermal Heat Pumps, or Ground Coupled Heat Pumps (GCHP), are systems combining a heat pump with a ground heat exchanger (closed loop systems), or fed by ground water from a well (open loop systems). They use the earth as a heat source when operating in heating mode, with a fluid (usually water or a water-antifreeze mixture) as the medium that transfers the heat from the earth to the evaporator of the heat pump, thus utilizing geothermal energy. In cooling mode, they use the earth as a heat sink. With Borehole Heat Exchangers (BHE), geothermal heat pumps can offer both heating and cooling at virtually any location, with great flexibility to meet any demands. More than 20 years of R&D focusing on BHE in Europe has resulted in a wellestablished concept of sustainability for this technology, as well as sound design and installation criteria. Recent developments are the Thermal Response Test, which allows in-situ-determination of ground thermal properties for design purposes, and thermally enhanced grouting materials to reduce borehole thermal resistance. For cooling purposes, but also for the storage of solar or waste heat, the concept of underground thermal energy storage (UTES) could prove successful. Systems can be either open (aquifer storage) or can use BHE (borehole storage). Whereas cold storage is already established on the market, heat storage, and, in particular, high temperature heat storage (> 50°C) is still in the demonstration phase. Despite the fact that geothermal heat pumps have been in use for over 50 years now (the first were in the USA), market penetration of this technology is still in
Fuel and Energy Abstracts May 2004 209
04/01535 Podhale (South Poland) geothermal district heating system Dlugosz, P. Geothermics, 2003, 32, (4-6), 527-533. The search for geothermal resources in the Podhale Region began in the late 1980s. The Banska IG-1 well, drilled in 1981, served as the starting point for an expansion of those research activities. A geothermal pilot plant was put into operation in 1993. During that same year the company Geotermia Podhalanska (GP) was founded and the pilot project, including the first distribution network for 20 customers, was constructed. After the initial phase of project implementation from 1993 to 1995, during which a pilot plant was constructed and put into operation for demonstration purposes by the Polish Academy for Sciences using the first geothermal doublet (a production well in Banska Nizna and a reinjection well in Bialy Dunajec), and connection of 200 households through a small district heating network, the World Bank got involved in the geothermal district heating project. Since then, significant progress has been made, increasing the overall heat capacity and geothermal output as well as the service area to the City of Zakopane, approx. 14 km from the production wells. In November 2001 the first geothermal heat was delivered to customers in Zakopane.
04•01536 Representative building design and internal load patterns for modelling energy use in residential buildings in Hong Kong Wan, K. S. Y. and Yik, F. H. W. Applied Energy, 2004, 77, (1), 69-85. Based on the data collected in recent surveys, models have been established to represent the energy characteristics of living and dining rooms and bedrooms in typical residential buildings in Hong Kong, in respect of the layout and construction; the density and pattern of occupation; the power intensities and operating patterns of lighting and appliances; and air-conditioner operation patterns. With the help of computer simulation, the impacts of varying these characteristics on the annual space cooling load have been evaluated, which allowed representative internal load patterns for residential units to be defined. These are essential data for predicting energy use in residential buildings, which, in turn, is an indispensable part of studies on ways to assess and minimize energy use in such buildings. This paper presents the building model and the internal load and air-conditioner operation patterns established in the study.
04/01537 Subsystem level fault diagnosis of a building's air-handling unit using general regression neural networks Lee, W.-Y. et al. Applied Energy, 2004, 77, (2), 153-170. This paper describes a scheme for on-line fault detection and diagnosis (FDD) at the subsystem level in an Air-Handling Unit (AHU). The approach consists of process estimation, residual generation, and fault detection and diagnosis. Residuals are generated using general regression neural-network (GRNN) models. The G R N N is a regression technique and uses a memory-based feed forward network to produce estimates of continuous variables. The main advantage of a G R N N is that no mathematical model is needed to estimate the system. Also, the inherent parallel structure of the GRNN algorithm makes it attractive for real-time fault detection and diagnosis. Several abrupt and performance degradation faults were considered. Because performance degradations are difficult to introduce artificially in real or experimental systems, simulation data are used to evaluate the method. The simulation results show that the GRNN models are accurate and reliable estimators of highly non-linear and complex A H U processes, and demonstrate the effectiveness of the proposed method for detecting and diagnosing faults in an AHU.
04/01538
The use of downhole heat exchangers Lund, J. W. Geothermics, 2003, 32, (4-6), 535-543. The downhole heat exchanger (DHE), used extensively in Klamath Falls, Oregon, in over 500 installations, and in Turkey and New Zealand, provides heating for one or more homes, schools, and apartment buildings from a single geothermal well. The D H E eliminates the problem of disposal of geothermal fluid, since only heat is extracted from the well. The heat exchangers consist of a loop of pipes or tubes suspended in the geothermal well, through which 'clean' secondary water is pumped or allowed to circulate by natural convection. The maximum output of large installations is typically less than 3 GJ/h or 0.8 MWt, with well depths up to about 150 m, and may be economical under certain conditions at a well depth of 500 m. However, the typical output for an individual home in Klamath Falls tends to be less than 265 MJ/h (0.07 MWt). In order to obtain maximum output, the well must be designed to have an open annulus between the wellbore and casing, with perforations near the top and bottom of the submerged heat exchanger, just below the water surface and at the hot aquifer at the bottom of the well. Natural convection circulates the well water down inside the casing, through the lower perforations, up through the annulus and back into the casing through the upper perforations, with the new geothermal water mixing with the old. This vertical convection cell exposes the D H E to the near-
maximum temperature of the well water and thus increases the heat output of the DHE. The heat output from a D H E system is dependent on the bore diameter, casing diameter, D H E length, tube diameter, number of loops in the well, flow rate and temperature of the geothermal fluid. Based on local experience in Klamath Falls, the 'ruleof-thumb' is that contractors estimate approximately '1 foot of D H E pipe per 1500 Btu/h' (5200 kJ/h/m or 1.44 kW/m) as an average output.
04/01539 Using small reverse cycle air conditioners in relocatable classrooms - a case study Fuller, R. J. and Luther, M. B. Energy and Buildings, 2003, 35, (6), 619629. A 9-month study of four relocatable school buildings, each retro-fitted with small reverse cycle air conditioners (ACs), was conducted to investigate their effectiveness in heating and cooling the classrooms. A comparison with data from previous studies found the energy used by the ACs for heating these temporary classrooms was only 19-20% of the energy used by individual gas heaters installed in permanent classrooms. When equipment efficiencies were considered, the AC units supplied 20-27% less energy to heat the classrooms. The possible reasons for this reduction in supplied energy are explored in this paper. CO2 emissions for the AC units in heating mode, however, were calculated to be 16% greater than for individual gas heaters. The AC units were also used for cooling and on an average the total annual energy consumption for heating and cooling was found to be 11.6 kWh m -z. Responses to a small survey of staff and students about the use and operation of the conditioners are presented. Their responses were more favourable than the predictions of comfort levels in the classrooms using the Predicted Mean Vote-Predicted Percentage of Dissatisfaction (PMV-PPD) model, which indicated 'uncomfortable' conditions on average summer days at 3:00 p.m. and average winter days at 10:00 a.m. Background noise levels in the classrooms with the air conditioners in use were above the recommended maximum design level of 45 dB(A); levels of up to 65 dB(A) were measured.
14
HEAT P U M P S
04/01540 Characteristics of an improved heat-pump cycle for cold regions Ma, G. and Chai, Q. Applied Energy, 2004, 77, (3), 235-247. To increase the heating capacity of air-source heat-pump in cold regions, an improved heat pump cycle with scroll compressor economizer was developed. The measured results of the prototype demonstrate that it can provide a high temperature and high-capacity water supply even under a low ambient temperature of - 1 0 ~ - 1 5 ° C . The performances of the improved heat-pump cycle are comprehensively analysed with aid of the proposed thermodynamic model in this paper. The design parameters and the components of the cycle are optimized and the predicted results. The predicted results discussed indicate that the improved heat pump has high efficiency under all weather conditions and that this improvement is conducive to enlarging the running region of the heat pump and providing an alternative heating service for cold regions.
04/01541 Current status of ground source heat pumps and underground thermal energy storage in Europe Sanner, B. et al. Geothermies, 2003, 32, (4-6), 579-588. Geothermal Heat Pumps, or Ground Coupled Heat Pumps (GCHP), are systems combining a heat pump with a ground heat exchanger (closed loop systems), or fed by ground water from a well (open loop systems). They use the earth as a heat source when operating in heating mode, with a fluid (usually water or a water-antifreeze mixture) as the medium that transfers the heat from the earth to the evaporator of the heat pump, thus utilizing geothermal energy. In cooling mode, they use the earth as a heat sink. With Borehole Heat Exchangers (BHE), geothermal heat pumps can offer both heating and cooling at virtually any location, with great flexibility to meet any demands. More than 20 years of R&D focusing on BHE in Europe has resulted in a wellestablished concept of sustainability for this technology, as well as sound design and installation criteria. Recent developments are the Thermal Response Test, which allows in-situ-determination of ground thermal properties for design purposes, and thermally enhanced grouting materials to reduce borehole thermal resistance. For cooling purposes, but also for the storage of solar or waste heat, the concept of underground thermal energy storage (UTES) could prove successful. Systems can be either open (aquifer storage) or can use BHE (borehole storage). Whereas cold storage is already established on the market, heat storage, and, in particular, high temperature heat storage (> 50°C) is still in the demonstration phase. Despite the fact that geothermal heat pumps have been in use for over 50 years now (the first were in the USA), market penetration of this technology is still in
Fuel and Energy Abstracts May 2004 209