Wyniki wyszukiwania - BazTech

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Dual ORC-Brayton power system for waste heat recovery in heavy-duty vehicles

Cholewiński M., Pospolita W., Błoński D.

Archives of Transport

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2016

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Vol. 39, iss. 3

7--19

EN

Reducing the amount of energy required in industrial activities is one of the proven ways to achieve major cost savings, especially in the face of soaring energy prices. In the transport sector, besides the financial benefits, low energy consumption leads to the significant reduction of emissions of many pollutants. In this paper the new concept of dual power technology, dedicated to heavy road transport, was modelled and analysed by computer simulations. The combination of organic Rankine cycle and Brayton cycle was proposed, where the waste heat of fumes was recognized as a upper heat source, whereas the surrounding was adopted to be the lower one. Improvement of total energy conversion efficiency of the truck was the key success factor. Environmental friendly fluids (air and R123) were utilised. The operating parameters, power characteristics and energy streams (i.e. dispersion) of the system were evaluated, calculated and commented from the perspective of its theoretical profitability. The calculated net power capacity of analysed dual system was around 50 hp for 100% load. However, when the engine load is below 50% of nominal capacity, the power generation of combined system might be lower than in the case of single ORC system.

2

Selected technical problems of cogeneration of electric energy and heat

Lampart P.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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2014

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nr 145

77--78

EN

Cogeneration as a simultaneous production of electric energy and heat brings a considerable increase of energy efficiency and contributes to decrease emissions of harmful gases into the environment. Cogeneration can be applied in a large and small scale, however the opportunities for cogeneration are usually determined by the demand on heat. The prime movers in the large-scale cogeneration are steam turbines operating in a closed Rankine cycle. Extraction-condensing turbines provide the possibility of flexible coping with heat demand with practically little loss to the electric energy production. In order to take full advantage of variable load operation in extraction-condensing turbines, their adaptive control is needed and will be discussed in the paper. Cogeneration can especially be applied in small power units of distributed generation systems. In small (and micro) units, the produced energy goes first to local communities. One can mention here the energy generation for households, residence buildings, large farms, public buildings or small and medium enterprises. The surplus of electric energy goes to the power network, whereas heat surplus goes to local district heating networks. There are many different technologies available for cogeneration of electric energy and heat in distributed sources such as gas/biogas stations, pv/solar instalations, biorafinery, biomass stations. The paper describes an idea of a multi-fuel cogeneration system, which is a local energy centre for a small municipal community that includes a biomass-fueled steam power unit, ORC power unit, a group of gas piston engines and a coal boiler. ORC is a promising technology for cogeneration based on local energy resources. ORC power units can be used as a main generation system allowing utilisation of different types of fuels. The solution also offers a possibility to apply low temperature heat sources. Therefore, ORC can be applied for topping main generation systems, for example based on piston engines or gas turbines. In the first case a heat source is usually a biomass-fueled boiler, whereas in the latter case ORC operates on a recovery heat coming from the exhaust gases and/or engine cooling system. The ORC unit working in a combined cycle allows for a considerable increase of electric energy production. In the framework of the strategic programme of the Polish National Centre for Research and Development (NCBiR) two pilot installations with a considerable industrial potential are developed at IMP PAN: – a poligeneration ORC system of electric power 100 kW and heat power 400 kW being a model for an agro-energy complex. The system consists of a boiler, intermediate heat cycle, ORC unit with a turbine working on a silica oil MDM, orfice cooling unit and connection to electric and heating network. The system products electricity, heat and cold; – a cogeneration gas/ORC unit of electric power 0.45 MWe with a gas piston engine topped by an ORC unit. The recovery boiler is installed to transport heat from exhaust gases to the low-temperature ORC unit working on a medium SES36, whereas the heat from cooling the piston engine is used for network heating.

3

Steam bottoming cycles offshore - challenges and possibilities

Nord L. O., Bolland O.

Journal of Power Technologies

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2012

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Vol. 92, nr 3

201--207

EN

This paper addresses the challenges and possibilities related to offshore steam bottoming cycles with a special focus on once-through heat recovery steam generators (HRSGs). The main focus of the paper is to investigate the compromise between weight and efficiency of the HRSG by process simulation. The cost per installed kg of equipment is high offshore. Therefore, any bottoming cycle, applied to the back-end of the gas turbine, needs to be compact, yet sufficiently efficient. Important parameters to make the HRSG compact were the number of steam pressure levels, the HRSG technology, the flue gas pressure drop in the HRSG, and the pinch-point temperature difference. While selecting the parameters as a compromise between weight and efficiency, the combined cycle net plant efficiency was found to be approximately 50% with a power output of 43 MW. The steam turbine gross power output was 11 MW or about 25% of the total combined cycle plant gross power output. These results were compared to an onshore reference plant model which utilized the same type of aeroderivative gas turbine. The weight of the offshore once-through HRSG was about one third of the onshore HRSG. The net plant efficiency was 3%-points lower for the offshore system.