Mergner H.,EnBW |
Weimer T.,Makatec GmbH
Energy | Year: 2015
Cost efficient power generation from low temperature heat sources requires an optimal usage of the available heat. In addition to the ORC (Organic Rankine Cycles), cycles with ammonia and water as working fluid show promising results regarding efficiency. Due to their non-isothermal phase change, mixtures can adapt well to a liquid heat source temperature profile and reduce the exergetic losses. In this analysis thermodynamic calculations on the layouts of two existing ammonia-water cycles are compared: a geothermal power plant based on a Siemens' patent and a modified lab plant based on a patent invented by Kalina (KCS-34). The difference between the two cycles is the position of the internal heat recovery. Cycle simulations were carried out at defined boundary conditions in order to identify optimal operation parameters. For the selected heat source of 393.15K (hot water) the ammonia mass fraction between 80% and 90% results in the best performance in both configurations. In general, the layout of Siemens achieves a slightly better efficiency compared to the KCS-34. Compared to an ORC using R245fa as working fluid, the exergetic efficiency can be increased by the ammonia/water based cycles by approximately 25%. © 2015 Elsevier Ltd.
Weimer T.,Makatec GmbH |
Piazzesi G.,Ecole Polytechnique Federale de Lausanne
Proceedings of the 27th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2014 | Year: 2014
Cost efficient power generation from low temperature heat sources is always challenging. But in combination with heat recovery from aggressive gases the challenge is becoming even more ambitious. Especially for acidic gases, one solution could be to use a polymer heat exchanger. Beside the heat transfer performance and the long term chemical stability, the pressure drop for the gas flow is a crucial issue for this application. Already some mbar of pressure drop can lead to a power consumption of the flue gas fan higher than the one generated in the power cycle. Two types of polymer spiral heat exchangers have been developed and tested for heat recovery. The first type uses polymer films as channel wall and biaxial meshes to stabilize the channel geometry; the second consists mainly of wounded capillary tubes. For maximum temperatures below 95 °C low cost Polypropylene can be used, at higher temperatures high performance polymers should be selected. Experimental results for the pressure drop and heat transfer of preliminary prototypes are presented, as well as a suitable scale up strategy for MW scale heat exchangers. A future development of a gas heated polymer based evaporator could help to make power generation from aggressive low temperature heat sources more economic in the future.
Schulacks A.,Makatec GmbH
CIT Plus | Year: 2010
Usually plastic heat exchangers have poor heat transfer values and low resistance to pressure. The plastic heat exchanger of the Makatec Apparate company however approaches the performance of conventional metal heat exchangers. It also has a higher heat transfer coefficient than other plastic heat exchangers on the market. This has been achieved by the use of an ingenious flow path and a special construction in plastic material. Designed for use with liquids, this heat exchanger is pressure stable up to 6 bar. Higher pressures are possible for which a PN-16 version is being developed. It has corrosion resistance and little fouling danger. The self insulating effect of its construction make it most suitable for uses involving aggressive fluids. In a tungsten upgrading application an alcohol-tungsten mixture is condensed via cold water. The abrasive effect of the tungsten leads to leakage in a short time. In a test with Makatec plastic heat exchangers the inert surface of the plastic material has led to a longer service life without abrasion and wear. Another use in the chemical industry relates to an acid of pH 1 with high fraction of metal salts to be cooled from 70 to 20°C. During cooling in metal heat exchangers, salts deposit on the walls of the heat exchangers that then must be dismantled and cleaned. This expense can be reduced by the use of Makatec plastic heat exchangers. The polymer materials resist corrosion and attacks from the acid, salts do not crystallize on the smooth surface, and the plastic material is usually not sensitive to abrasion. The lengthening of the heat exchanger service life and the reduced number of maintenance cycles reduce the costs in this chemical application.
Agency: Cordis | Branch: FP7 | Program: BSG-SME | Phase: SME-1 | Award Amount: 1.44M | Year: 2011
There are about 500 000 professional fire fighters in the European Union (EU). When called to fight fires they can be exposed to high levels of heat stress, which results in decreased physical performance and even heat exhaustion. If a fire fighter succumbs to heat exhaustion he requires rescuing and this then exposes other fire fighters and the public to increased risk. In order to reduce the risk of heat stress, the firefighters are limited to the time they can be at the fire which increases the number of fire fighters needed to fight a fire and this reduces efficiency and introduces complication into the communications between the crews fighting the fire. The StayCool project will develop and prototype a novel system for cooling the body that is light weight, has low energy consumption and so can be worn for prolonged periods of time. Wearing the StayCool system will reduce the wearers core temperature and allow fire fighters to stay at the fire for greater periods of time and so improve the efficiency of fighting the fire, extinguishing the fire quicker and so reduce risk of loss of life and damage to property. The StayCool partnership is ideally placed to develop and exploit this technology having expertise in protective clothing design and manufacture, physiological and human factors testing, mathematical and thermodynamic modeling, access to rapid prototyping and manufacture facilities and the ability to design for manufacture to ensure the StayCool system can be fully exploited. The StayCool system is primarily aimed at a launch market for fire fighters but there e are a number of applications where humans need to work in high ambient temperatures. Additional markets for this technology and associated products include industrial plant operators, miners, underground maintenance, nuclear decommissioning, general policing in hot climates, policing in protective equipment and for use in extreme sports.
Agency: Cordis | Branch: FP7 | Program: BSG-SME | Phase: SME-1 | Award Amount: 1.60M | Year: 2010
A core part of this proposal is the development of methodologies to select and rigorously design the appropriate type of enhancement technology into energy optimisation studies to a practical level, whereby process plant engineers can plan and carry out plant energy reduction programmes in which they will have confidence. The project aims to achieve at least 20% to 30 % energy savings in the energy recovery systems from the successful completion of the project, through: (i) Enhancing our understanding of heat exchange and waste heat recovery; (ii) Combining enhanced heat transfer innovative design to achieve the synergy of separate novel technologies with focus on conventional, plate-fin and membrane exchangers. Current trends will be taken into account that whilst new types of exchangers are making an increasing impact and acceptance in the process industry, the main exchanger types are based around tubular constructions, shell and tubes and air cooled exchangers and that it is likely to remain so for many practical and pressure withstanding reasons. (iii) Proposing new materials of improved economic and environmental performance as heat transfer media (with focus on advanced heat transfer fluids). (iv) Implementing the developed technologies effectively in heat exchanger networks (HENs) through intelligent process integration and control techniques.