Experimental investigations were carried out to determine the Al2O3/water and SiO2/water nanofluids flowing through a circular tube. convective heat transfer performance and pressure drop of Measurements show that the...Experimental investigations were carried out to determine the Al2O3/water and SiO2/water nanofluids flowing through a circular tube. convective heat transfer performance and pressure drop of Measurements show that the addition of small amounts of nano-sized Al2O3 particles to the base fluid increases heat transfer coefficients considerably, while the result for the silica nanofluids contradicts with the alumina nanofluids and this leads to some interesting results. In the case of alumina nanofluids, an average increase of 16% in convective heat transfer coefficient is observed with an average penalty of 28% in pressure drop. Moreover, flow resistance increases significantly compared to the base fluid even at very low concentrations of nanofluids. Finally, measured heat transfer coefficients are compared with predicted ones from the correlation of Shah under the same conditions.展开更多
Helsinki Environmental Services Authority HSY ,Ammaissuo waste management centre consists of two landfill sites. The old land filling area was established in 1987 and closed in 2007. The landfilling at the new landfil...Helsinki Environmental Services Authority HSY ,Ammaissuo waste management centre consists of two landfill sites. The old land filling area was established in 1987 and closed in 2007. The landfilling at the new landfill section started in November 2007. Until spring 2014 the main treatment method for source separated MSW （municipal solid＇waste） collected from Helsinki Metropolitan area households was landfilling. Approximately 250,000 tonnes of MSW was landfilled annually. From April 2014 on all of the MWS has been utilized in heat and electricity production at new Waste to Energy plant owned and operated by energy company Vantaa Energy Ltd. The landscaping of the landfills is currently ongoing. The construction of the landfill gas collection system was started in 1994 and from 1996 on landfill gas from old landfill area was recovered and burned in torches to reduce the greenhouse gas effect caused by methane in landfill gas. In the end of year （2004） new landfill gas utilisation system was taken in use Gas was used as a fuel in HOB （heat only boiler） to generate district heating for nearby community as well as commercial and industrial sites. The capacity of the system was 7,000 Nm3/h that corresponded to app. 30 MW of heat. Since district heat was mainly needed only during the cold season of the year only about half of the landfill gas produced by the landfill was able to utilize and rest of the gas was still flared leading to relatively low utilization rate of the gas. The construction work of the new 15 MW ＋ 1.2 MW electricity power plant started in spring 2009. The power plant consists of four gas engines and generators and organic rankine cycle process utilizing thermal oil for heat transfer from exhaust gas and steam turbine with hexamethyldisiloxane （silicone oil） as a medium agent. The ORC （Organic Rankine Cycle）-process was commissioned in August 2011 and the operational experiences have been very good. Based on current knowledge the HSY power plant is the biggest landfill gas fired power plant in Europe and probably even in the whole world. Also the combined engine and ORC-process is unique for landfill gas power plants. The third phase of the biogas utilization took place in summer 2015 when the anaerobic digestion biowaste treatment plant was introduced. At the moment the product gas from digestion plant is utilized at landfill gas power plant. In the future gas will be used as a fuel for new power plant process consisting two gas engines and ORC process. Commissioning of the new power plant will take place in October 2016. This paper presents detailed description of the landfill gas utilization system of HSY waste treatment centre and information on operational experiences of landfill gas fired power plant process.展开更多
文摘Experimental investigations were carried out to determine the Al2O3/water and SiO2/water nanofluids flowing through a circular tube. convective heat transfer performance and pressure drop of Measurements show that the addition of small amounts of nano-sized Al2O3 particles to the base fluid increases heat transfer coefficients considerably, while the result for the silica nanofluids contradicts with the alumina nanofluids and this leads to some interesting results. In the case of alumina nanofluids, an average increase of 16% in convective heat transfer coefficient is observed with an average penalty of 28% in pressure drop. Moreover, flow resistance increases significantly compared to the base fluid even at very low concentrations of nanofluids. Finally, measured heat transfer coefficients are compared with predicted ones from the correlation of Shah under the same conditions.
文摘Helsinki Environmental Services Authority HSY ,Ammaissuo waste management centre consists of two landfill sites. The old land filling area was established in 1987 and closed in 2007. The landfilling at the new landfill section started in November 2007. Until spring 2014 the main treatment method for source separated MSW （municipal solid＇waste） collected from Helsinki Metropolitan area households was landfilling. Approximately 250,000 tonnes of MSW was landfilled annually. From April 2014 on all of the MWS has been utilized in heat and electricity production at new Waste to Energy plant owned and operated by energy company Vantaa Energy Ltd. The landscaping of the landfills is currently ongoing. The construction of the landfill gas collection system was started in 1994 and from 1996 on landfill gas from old landfill area was recovered and burned in torches to reduce the greenhouse gas effect caused by methane in landfill gas. In the end of year （2004） new landfill gas utilisation system was taken in use Gas was used as a fuel in HOB （heat only boiler） to generate district heating for nearby community as well as commercial and industrial sites. The capacity of the system was 7,000 Nm3/h that corresponded to app. 30 MW of heat. Since district heat was mainly needed only during the cold season of the year only about half of the landfill gas produced by the landfill was able to utilize and rest of the gas was still flared leading to relatively low utilization rate of the gas. The construction work of the new 15 MW ＋ 1.2 MW electricity power plant started in spring 2009. The power plant consists of four gas engines and generators and organic rankine cycle process utilizing thermal oil for heat transfer from exhaust gas and steam turbine with hexamethyldisiloxane （silicone oil） as a medium agent. The ORC （Organic Rankine Cycle）-process was commissioned in August 2011 and the operational experiences have been very good. Based on current knowledge the HSY power plant is the biggest landfill gas fired power plant in Europe and probably even in the whole world. Also the combined engine and ORC-process is unique for landfill gas power plants. The third phase of the biogas utilization took place in summer 2015 when the anaerobic digestion biowaste treatment plant was introduced. At the moment the product gas from digestion plant is utilized at landfill gas power plant. In the future gas will be used as a fuel for new power plant process consisting two gas engines and ORC process. Commissioning of the new power plant will take place in October 2016. This paper presents detailed description of the landfill gas utilization system of HSY waste treatment centre and information on operational experiences of landfill gas fired power plant process.
