Usable Heat Research Articles

Sustainable Development through Waste Heat Recovery

Problem statement: Waste Heat Recovery (WHR) steam Technology is a proven Technology pioneered by Japanese for cement plant and it is economically viable. Electrical Power can be generated by adopting the latest technology in this field. It used a medium to low temperature (120-350°C) Turbine technology (standard thermal power plants run on steam temp-500°C). Approach: It requires treat exchangers (Hx) designed for high dust load, no additional fuel is required Kymore Cement Works has proposed to install a power plant of 9 MW which will be operated with the recovered waste heat from the clinker coolers and kilns from its both clinker units. The hot air from cooler and kiln passes through the ESP is taken to the waste heat recovery exchangers. Adequate size of heat-exchangers will be located at proper locations in order to achieve optimum temperature of Thermic Oil from waste gases. Conclusion/Recommendations: This is required for optimal power yield. The hot flue gases will pass through a Heat Exchanger by which the temperature (heat of the waste gas is transferred to the internal elements of the heat exchangers which is used for heating of the thermo oil. In turn this thermal oil vaporizes the organic fluid in close loop cycle. Multi level pressure turbine system will be installed which increases usable heat content resulting in higher power output. The turbine will be run by the organic vapors to generate the electrical energy. The system of oil collection, oil transfer to the vaporizer and its recycling process will be made for the complete recycling of the thermal oil.

Energy efficiency measures and conversion of fossil fuel boiler systems in a detached house

There is a large potential to reduce primary energy use and CO2 emissions from the Swedish building stock. Here detached houses heated by oil, natural gas or electric boilers were assessed. CO2 emissions, primary energy use and heating costs were evaluated before and after implementing house envelope measures, conversions to more efficient heating systems and changes to biomass fuel use. The study included full energy chains, from natural resources to usable heat in the houses. The aim was to evaluate the societal economic cost effectiveness of reducing CO2 emission and primary energy use by different combinations of changes. The results demonstrated that for a house using an electric boiler, a conversion to a heat pump combined with house envelope measures could be cost efficient from a societal economic perspective. If the electricity was based on biomass, the primary energy use was at the same time reduced by 70% and the CO2 emission by 97%. Large emission reductions were also seen for conversions from oil and gas boilers to a biomass-based system. However, for these conversions the heating cost increased, leading to a mitigation cost of around €50/tonne C avoided. The price of oil and natural gas greatly influenced the competitiveness of the alternatives. House envelope measures were more cost-effective for houses with electric boilers as the cost of energy for this system is high. The results are specific to a Swedish context, but also give an indication of the potential in other regions, such as northern European and large parts of North America, which have both a cold climate and a widespread use of domestic boilers.

Study of vibrational modes in superionic lithium oxide

Lithium oxide, like other superionics, finds several technological applications. These applications range from miniature light weight high power density lithium ion batteries for heart pacemakers, mobile phones, laptops computers, etc. to high capacity energy storage devices for next generation. It is also a leading contender for future fusion reactors to convert energetic neutrons to usable heat and to breed tritium necessary to sustain D–T (deuterium–tritium) reactions. In this work, the lattice dynamics of Li2O have been carried out to study the fast ion phase and the diffusion behavior of lithium and oxygen ions. The investigation of this simple material is a reference point for understanding more complex metal-oxides. A modified rigid ion model has been used to study the phonons in lithium oxide by considering the interatomic interactions up to third nearest neighbor. The calculated results are compared and analyzed with available experimental results.

Improve efficiency of thermal regenerators and VOCs abatement systems: An experimental and modeling study

Thermal regenerator systems are very effective devices for the abatement of volatile organic compounds (VOCs), mainly in industrial processes with high flow rates. In these units, VOCs are usually converted with air to CO 2, H 2O and usable heat. Thermal regenerators consist of two or more beds containing ceramic materials. Alternatively one bed absorbs and stores the heat from the hot gases while the other heats up an entering stream of raw gases. The regenerators allow to clean and purify raw gases, recovering the combustion heat. The optimization of the process reduces the amount of auxiliary fuel, minimizing operating costs. Thermal performances of the regenerator are investigated experimentally and numerically in this work. A one dimensional, two phases, dynamic model has been developed and validated on the basis of a properly designed set of experiments. In this way, it is possible to compare the thermal efficiency and pressure drops of different structured packing materials in different operative conditions. The role of dwell time, flow rate, specific area and heat capacity is analysed, mainly in terms of cyclical temperature conditions, with specific attention to the thermal efficiency of the unit. Moreover, the coupling of the regenerator model with a general and detailed kinetic scheme of pyrolysis and combustion of hydrocarbon species is also discussed and some preliminary simulations of VOCs abatement are also presented. This model is a very useful tool not only to evaluate the conversion level of different pollutants but also to prevent detrimental ignition processes inside the bed.

Nutrient removal and bio-energy production from Netley-Libau Marsh at Lake Winnipeg through annual biomass harvesting

Abstract The primary goal of this research study was to evaluate the concept of combining bio-power production and nutrient removal by yearly biomass harvesting during ice-covered periods at Netley-Libau Marsh on Lake Winnipeg. Depending on the extent of vegetation within the marsh on any given year, removal rates range from 1.026 to 1.368 kt (3.1–4.2% of total Red River loading to Lake Winnipeg) of total nitrogen and 188–227 t (3.8–4.7% of total loading) of total phosphorus by harvesting 60% of the marsh area and 75% of the emergent parts of the vegetation. The effective management of water levels within the marsh was critical for vegetation growth and diversity. Suggestions on biomass harvesting and utilization methods were provided and a number of technologies were examined for the conversion of the harvested biomass to energy. The power produced in these systems ranged from 1.75 to 4.71 MW and, for some of the technologies, usable cogeneration heat was produced as a potential added value. CO2 emission credits of 55.07 kt y−1 can be expected with possible additional GHG credits for methane and NOx displacement.

Computer Simulation of Heat Transfer in Regenerative Chambers of Self-preheating Hot Blast Stoves

Heat transfer in chambers of self-preheating hot blast stoves in Anshan Iron and Steel Co., China, has been numerically simulated with a three-dimensional unsteady heat conduction equation and an energy conservation equation for fluid flowing through channels in the chambers. The blast temperature and air preheating temperature in the numerical simulation study are in good agreement with those in measurement. The numerical results show that hot blast temperature can reach 1 200°C by using a self-preheating process and low calorific blast furnace gas under the studied operational conditions. Amount of heat exchange between the checkerwork and the fluids and usable heat increase in the middle and low parts of the chambers of the hot blast stoves due to the application of the self-preheating process.

Helio-hydro and helio-thermal production of hydrogen

Fossil fuels account for about 80% of the world annual energy demands. Renewables contribute 14% and nuclear some 6%. These numbers will soon change as the world's population grows, energy demand rises, cheap oil and gas deplete, global warming effects continue rising and city pollution worsens the living conditions. The development of energy sources and devices will emerge more aggressively to address the world's energy and environmental situation. A concept of using hydrogen as an energy carrier or storage as a fuel, a replacement of burning fluid fossil fuels is presented. Sources of energy from which hydrogen can be produced in a massive quantity and at a low cost are briefly surveyed. A short account of devices to be employed for hydrogen production is given. Primarily the sun, sea, runoff waters, winds and fissionable materials are to be utilized. The discussion on the inexhaustibility of naturally occurring sources utilized and/or harnessed in this process will lead to the low cost for hydrogen production. Some hydrogen rich products including hydrogen sulfide and methane accompany the oil, gas and brine, when they are pumped out of the ground. While methane is used sometimes as fuel; the hydrogen sulfide is disposed off invariably. In principle, hydrogen can be extracted from these waste products. We discuss here to produce hydrogen in economically feasible manner. The use of brine as a means of usable solar energy in the form of heat and electricity was discussed earlier. Here, we aim at discussing the production of hydrogen from the brine and hydrogen sulfide gas. The brine is proposed to be utilized for two purposes: one for salt gradient solar pond to produce usable heat and electricity, and the other as an electrolyte to produce hydrogen out of itself. The hydrogen from hydrogen sulfide can chemically be extracted.

Dynamic analysis of heat recovery process for a continuous heat recovery adsorption heat pump

The heat recovery cycle plays an important role in improving the operational performance of a continuous heat recovery adsorption heat pump. The real heat recovery ratio would be less than the ideal heat recovery ratio because of the limited heat transfer coefficient of the adsorber. In this paper, by dynamic calculation for a continuous heat recovery adsorption heat pump, the heat recovery ratio in different working conditions was determined. Meanwhile, the influence of adsorber heat transfer coefficient was analyzed, and the influences of system operation parameters, such as heat source temperature, cooling water temperature, cycle time and so on, on the heat recovery process were also analyzed. The way to increase the usable heat recovery effect was discussed.

Calculation of building heating demand in EPIQR

Calculations of energy requirements for space heating in EPIQR are based on an existing computer programme, made according to the European standard EN 832:1998. The programme was originally a stand-alone programme with its own user interface. This has been stripped of and the source code re-compiled into a dynamic link library (DLL) controlled by EPIQR. The method is based on a monthly calculation of heat losses and usable heat gains for the building. For the calculation, the monthly mean values of the external temperature and solar radiation are applied, and the heat gain from lighting and appliances, as well as the heat-accumulating capacity of the building, are taken into consideration. In EPIQR, some input parameters have been fixed to ensure that the user only has to supply simple input data to carry out a heating requirement calculation. This paper describes the applied calculation technique and the assumptions made in EPIQR to carry out heating requirement calculations and how energy-saving retrofit is evaluated using the software.

排熱回収のための蓄熱・ヒートポンプシステムにおけるゼオライト‐水組合せ

Huge amount of heat below about 200 °C, for example, has been exhausted in vain from various factories. Such unused heat sources including the solar heat must be used effectively to save consumption of fossil fuels. Although we generally encounter many technical difficulties to extract usable heat from such low temperature heat-sources, the zeolite-water-pair, that is, the nonlinear relationship between the vapor pressure and temperature, may give a prospective solution for the heat recovery.As zeolite-researchesstanding especially on the heat recovering aid have been lacking so far, several targets will be pointed out here on the present subject.

Large stationary microstrip arrays for superficial microwave hyperthermia at 433 MHz: SAR analysis and clinical data.

Superficial hyperthermia with present day applicators provides a challenge when tumours exceed several cm in diameter. Unless microstrip applicators are scanned, the usable heat region often falls short of treating the entire region with 50% power or specific absorption rate (SAR). New microstrip applicator designs were evaluated through SAR analysis and compared to the traditional microstrip applicators used in the clinic at Dartmouth over the past six years. The new designs included fabricating thin archimedean spirals (1.0 mm strip width) incorporating dielectric substrate (epsilon = 5.3-10.8). The designs were optimized at 433 MHz for an arm length of 59 cm. Measurements in a plane 1.0 cm from the surface showed that thin spirals outperformed traditional designs by increasing the 50% SAR area by a factor of 2.5, while maintaining the same physical size. Arrays of four elements were fabricated from thin spirals, although SAR evaluation showed only 10-20% SAR between elements. Since this was deemed unacceptable and the design goal was to fabricate a stationary applicator that had at least 50% SAR between elements, dual element designs were created with gradually overlapped elements. It was found that overlapping three coils of the spiral created a large region that equalled or exceeded 50% SAR that could not be matched by single applicators. Coherent operation of the dual spiral array resulted in more central power deposition and incoherent operation resulted in more peripheral power deposition. SAR measurements at the fat/muscle interface showed an elongated heating pattern in hydroxyethylcellulose muscle equivalent phantom. Power deposition 1.0 cm deep in muscle retained the same basic size and shape with or without the fat layer. Patient treatments for chestwall tumours confirmed that the dual overlapping applicator heated a larger region without the sharp temperature peak associated with single applicators.

Fuel substitution and efficient woodstoves: Are they the answers to the fuelwood supply problem in Northern Nigeria?

Fuelwood consumption in Northern Nigeria exceeds the sustainable production, and the deficit is currently met through long-distance transport from the southern part of the country at an artificially low cost Current household fuel consumption patterns and factors affecting stove choice are discussed. Little has been done to promote more efficient woodstoves in the region, but prospects for stove programs are only good where fuelwood is marketed and the policy environment is conducive. At subsidized official prices for kerosene, liquefied petroleum gas (LPG), and electricity, wood is more expensive on a net usable heat basis, but the high capital cost of stoves for these fuels prevents many households from switching. Moreover, these fuels are often only available at much higher parallel market prices, which result in wood being the less expensive choice. There is little prospect for substitution of coal, solar cookers, or biogas digesters.

A procedure for estimating the value of forest fuels

The gross calorific value (or ‘higher heating value’) of fuelwood is typically 18·6 MJ kg −1 of dry wood. But the heat energy actually available from combustion of freshly-harvested fuelwood may be as low as 5·9 MJ kg −1. For this reason, there is a tendency to overestimate the true energy and economic values of forest biomass with respect to commercial energy sources. This paper interprets the main conventions used in quoting fuel values, and derives simple formulae (and graphs) for estimating energy contents of fuelwood at any given moisture level. The ‘usable heat content’ approach is developed as an equitable basis for comparing fuel values, and here provides energy and economic equivalents for wood, oil, coal, natural gas and peat.

Energy Evaluation of an Ultra‐High Temperature Shell‐and‐Tube Processing System

ABSTRACTEnergy loads for a shell‐and‐tube ultra‐high temperature (UHT) processing system were examined during start‐up, equipment sterilization and product processing. Product flow rates were 606, 1022, and 1325 L/hr. Process temperatures were 138, 143, and 149°C. The regeneration section contributed from 57.5–70.4% useable heat. Energy use remained relatively constant for varying start‐up conditions and increased as a function of flow rate during equipment sterilization. Energy inputs for product processing varied from 358–437 kJ/kg. Minimum energy loads occurred between flow rates of 1000 and 1250 L/hr. Longer processing times decreased the effect of equipment start‐up and sterilization on overall process energy requirements.

Use of waste water heat for supply water heating by use of heat pipe diodes

A hot supply water storage tank, which is heated by waste water heat, has been developed by Dornier System GmbH under a Daimler-Benz AG contract. Copper heat pipes using water as carrier fluid have been developed for this purpose, which are capable to transfer sufficient heat even at temperatures as low as 10°C. Measurements indicate that up to 90% of the usable waste water heat may be recovered depending upon the waste water flow rate and on the complexity of the system. Stratification within the tank allows that more than 75% of the stored energy may be drawn without a significant drop in supply water temperature.

Lighting with sunlight using sun tracking concentrators

The use of controlled beams of sunlight for lighting interior parts of a building is proposed as an economically attractive and practical option in a solar energy context. Sun tracking concentrators introduce beams of sunlight through holes in the roof. Inside, the beams can be relayed throughout the building by means of mirrors and lenses. Ideally cool lighting is obtained by using dielectric mirrors to separate the visible and ir parts of the solar spectrum. The ir can be used to generate electricity and usable heat in solar cells. Results of a preliminary experiment are given.