As the energy landscape changes globally with the development of tight oil and gas resources, questions about the rail safety and tighter regulations around safety and environment, energy insiders are asking the question; are pipelines still the safest way to transport energy? In a recent study conducted by T.D. Williamson (TDW) (1) this paper uncovers some current industry trends, drivers and restraints that will shape the pipelines landscape for the future. The study looked at regional trends, technology applications and future project developments in the pipelines arena and how this is influencing how pipelines are being designed, installed and utilized. The study identified that there were four distinct pipeline “themes” over the pipeline life cycle, which comprise: • Infrastructure – pipeline new build for growth, replacement and expansion, • Integrity Management – management of the integrity for new and existing pipelines, • Flow Assurance & Throughput – optimizing throughput and uptime for new and existing pipelines, • Management of Human Capital – acquiring, developing and retaining competent people or outsourcing. The paper will discuss how these needs imbedded in these themes are met or, as in some cases, unmet. The paper also looks at developments in materials for new pipelines, pipeline monitoring and leak detection (from cables to dogs to, unmanned vehicles), newer products that are being shipped (from higher hydrogen content methane gas to carbon dioxide from capture schemes to diluted bitumen from the oil sands), the impact of “big data” (from Mb to Yb), and how operators are looking to manage emergencies (from spill response to emergency planning and operational readiness). This paper will compare safety records for energy transportation as well as the new demands being put on energy companies that will propose an answer to the question posed in the title.

This study investigates the effect of combustion phase (premixed and diffusion phases) duration on the emissions emitted from a high speed direct injection (HSDI) diesel engine fueled with neat (100%) rapeseed methyl ester (RME) and run at a constant speed (1500 rpm) with single injection strategy at constant fuel injection pressure (800 bar) and varying fuel injection timings (−12,−9,−6,−3,0) ATDC, for two loads (2.5 and 5 bars) BMEP. The obtained results were compared with those obtained when the engine run at the same conditions but with ultra-low sulfur diesel fuel (ULSD). In-cylinder pressure was measured and analyzed using (LABVIWE) program. calculation program specially written in (MATLAB) software was used to extract the apparent heat release rate, the ignition delay, combustion duration and specify the amount of heat released during the premixed and diffusion combustion phases (premixed burn fraction PMBF) and (diffusion burn fraction DBF). Emission measurements included; NO x , CO, THC, CO 2 and smoke number (SN). The results showed that at high load, RME generate higher NO x , CO and THC. Measurements and calculations indicated that ignition delay of RME was shorter than that of ULSD, which means less PMBF. This conflicting effect is probably due to the advanced start of combustion (SOC) leading to higher combustion temperature inside the combustion chamber and there will be less time available to complete the combustion. The emission results at low load showed that NO x and CO, generated by RME were less than those generated by USLD. USLD produced soot more than RME at high load and less at low load.

When flying at hypersonic speeds, it is a fundamental requirement to reduce the high drag resulting from a blunt nose cone in the ascent stage to increase the payload weight on the one hand and decrease the amount of energy needed to overcome the Earth’s gravity on the other. However, an aerospike can be attached on the front of the nose cone to obtain a high drag and heat load reduction. This study describes novel technique of an active flow control concepton nose cone with aerodisk that uses counterflowing jets to significantly modify external flowfields. In fact, this method strongly disperse the shock waves of supersonic and hypersonic vehicles to reduce aerothermal loads.Numerical simulations of a 2D axisymmetric aerodisked nose cone in hypersonic flow are conducted, and innovative techniques involving forward injection of gas from the stagnation point of the sphere are investigated; techniques include injection of various counterflowing jets (Helium and Carbon dioxide) as a coolant jet from the nose cone behind the aerodisk. In this study, the characteristics of the various jet conditions of a counterflowing jet on a cone surface were investigated numerically to improve performance of the jet on heat reduction at surface of a nose. Different Mach numbers at different altitudes have been chosen to investigate the effect of the aerospike on the nose cone’s surrounding flowfield. The drag and the heat load reduction is numerically evaluated at Mach numbers of 5.75. The results show that the lighter gas, Helium, is found to have a better cooling performance than Carbon Dioxide in low pressure ratios. The film cooling of Helium jet due to its lower specific heat capacity (Cp) character is efficient on heat load of the nose cone.

Global warming and depletion of fossil fuels have compelled the researchers to study the sources of renewable energy. Biogas, one of the most promising alternative renewable biofuel, is produced from anaerobic digestion. It mainly consists of methane and carbon dioxide (CO 2 ) with traces of water vapor, hydrogen sulfide (H 2 S), siloxanes, hydrocarbons, ammonia, oxygen, carbon monoxide and nitrogen. The presence of high concentration of CO 2 in biogas lowers the energy content per unit mass/volume. This limits its utility to only low quality energy applications where as H 2 S is a highly toxic and corrosive gas. Therefore, it is extremely difficult to transport and store biogas. Thus, the need emerges for a unified approach for scrubbing, compression and subsequent storage of biogas for wider applications. The current work presents the scrubbing of biogas using the method of adsorption. The quality of the scrubbed biogas studied by gas chromatography is presented. The scrubbed biogas is then tested in a dual fuel diesel engine as a primary fuel to evaluate the performance and emission characteristics of the engine. The data obtained are compared with those of raw biogas run dual fuel diesel engine.

When the Norwegian government introduced the CO 2 tax for hydrocarbon fuels, the challenge became to improve the performance of off-shore power systems. An oil and gas platform typically operates on an island (stand-alone system) and the power demand is covered by two or more gas turbines. In order to improve the plant performance, a bottoming cycle unit can be added to the gas turbine topping module, thus constituting a combined cycle plant. This paper aims at developing and testing the numerical model simulating the part-load and dynamic behavior of a novel power system, composed of two gas turbines and a combined gas turbine coupled with an air bottoming cycle plant. The case study is the Draugen off-shore oil and gas platform, located in the North Sea, Norway. The normal electricity demand is 19 MW, currently covered by two gas turbines generating each 50% of the power demand, while the third turbine is on stand-by. During oil export operations the power demand increases up to 25 MW. The model of the new power plant proposed in this work is developed in the Modelica language using basic components acquired from ThermoPower, a library for power plant modelling. The dynamic model of the gas turbine and the air bottoming cycle turbogenerator includes dynamic equations for the combustion chamber, the shell-and-tube recuperator and the turbine shafts. Turbines are modelled by the Stodola equation and by a correlation between the isentropic efficiency and the non-dimensional flow coefficient. Compressors are modelled using quasi steady-state conditions by scaling the maps of axial compressors employing a similar design point. The recuperator, which recovers the exhaust heat from the gas turbine, is modelled using correlations relating the heat transfer coefficient and the pressure drop at part-load with the mass flow rate. Thermodynamic variables and dynamic metrics, such as the rise time and the frequency undershooting/ overshooting, are predicted. Considering a load ramp of 0.5 MW/s, an undershooting of 4.9% and an overshooting of 3.0% are estimated. The rise time is approximately 30 s. Moreover, findings suggest that decreasing the core weight of the recuperator leads to limiting the frequency fluctuations, thus minimizing the risk of failure of the power system.

Solar Heating and Cooling systems are a virtuous alternative to conventional air conditioning plants, as a renewable energy source (solar energy) is exploited. In this paper the coupling of low temperature solar devices with an innovative desiccant-based air handling unit, which meets the sensible and latent loads of a simulated lecture room, is analyzed through TRNSYS dynamic simulation software. The components have been characterized by means of experimental tests carried out at the test facility of Università degli Studi del Sannio. The desiccant-based air handling unit current set-up allows summer operation only. However, heating operation is also simulated, as comfort conditions can be maintained in the conditioned space exploiting solar thermal energy also in winter, with some modifications to the air handling unit. A parametric analysis is performed to compare different technical solutions (collector types, surface, tilt angle) and to identify the optimal one, taking into account energy, economic and environmental performance with respect to a reference system. The best case in terms of energy and environmental performance is represented by evacuated collectors, achieving a primary energy saving of 64% and a CO 2 emissions reduction of 61%; flat-plate collectors are instead the best solution in terms of pay-back period (6 years).

Reducing carbon dioxide (CO 2 ) emissions from power plants utilizing fossil fuels is expected to become substantially more important in the near- to medium-term due to increasing costs associated to national and international greenhouse gas regulations, such as the Kyoto protocol and the European Union Emission Trading Scheme. However, since net efficiency penalties caused by capturing CO 2 emissions from power plants are significant, measures to reduce or recover efficiency losses are of substantial interest. For a state-of-the-art 400 MW natural gas-fueled combined cycle (NGCC) power plant, post-combustion CO 2 removal based on chemical solvents like amines is expected to reduce the net plant efficiency in the order of 9–12 percentage points at 90% overall CO 2 capture. A first step that has been proposed earlier to improve the capture efficiency and reduce capture equipment costs for NGCC is exhaust gas recirculation (EGR). An alternative or complementary approach to increase the overall plant efficiency could be the recovery of available low temperature heat from the solvent-based CO 2 removal systems and related process equipment. Low temperature heat is available in substantial quantities in flue gas coolers that are required upstream of the CO 2 capture unit, and that are used for exhaust gas recirculation, if applied. Typical temperature levels are in the order of 80°C or up to 100 °C on the hot end. Additional low-grade heat sources are the amine condenser which operates at around 100–130 °C and the amine reboiler water cooling that could reach temperatures of up to 130–140°C. The thermal energy of these various sources could be utilized in a variety of low-temperature heat recovery systems. This paper evaluates heat recovery by means of an Organic Rankine Cycle (ORC) that — in contrast to traditional steam Rankine cycles — is able to convert heat into electricity efficiently even at comparably low temperatures. By producing additional electrical power in the heat recovery system, the global performance of the power plant can be further improved. This study indicates a theoretical entitlement of up to additional 1–1.5 percentage points in efficiency that could be gained by integrating ORC technology with a post-combustion capture system for natural gas combined cycles. The analysis is based on fundamental thermodynamic analyses and does not include an engineering- or component-level design and feasibility analysis. Different ORC configurations have been considered for thermal energy recovery at varying temperature levels from the above-mentioned sources. The study focuses on simultaneous low-grade heat recovery in a single ORC loop. Heat recovery options that are discussed include in series, in parallel or cascaded arrangements of heat exchangers. Different organic operating fluids, including carbon dioxide, R245fa, and N-butane were considered for the analysis. The ORC performance was evaluated for the most promising organic working fluid by a parametric study. Optimum cycle operating temperatures and pressures were identified in order to evaluate the most efficient approach for low temperature heat recovery.

On the road transportation sector, considering its deep involvement with many social expectations, assumed such proportions to become one of the major source of air pollution, mainly in urban highly congested areas. The use of reciprocating internal combustion engines (ICE) dominates the sector and the environmental dimension of the problem is under a strong attention of Governments. European Community, for instance, through sequences of regulations (EURO) reduced the emission allowed of primary pollutants; more recently, the Community added limits to climate-altering gases which directly refer to fuel consumption reduction. These limits today appear the new driver of the future engine and vehicle technological evolution. Similar efforts are under commitment by other developed countries (USA, Japan, etc,…) as well as also by the other Countries whose economic importance will dominate the markets in a very near future (BRICS Countries). The need to fulfill these issues and to keep the traditional engine expectations (torque, speed, fun to drive, etc..) triggered, especially in recent decades, a virtuous cycle whose result will be a new engine and vehicle era. The evolution till had today has been driven by the EURO limits and it demonstrated surprisingly that emission reduction and engine performances can be matched without compromises in both sides. Today, adding severe limits on equivalent CO 2 , emissions, it appears very difficult to predict how future engines (and vehicles) will be improved; new technologies are entering to further improve the traditional thermal powertrain but the way to a massive and more convinced electrification seems to be definitely opened. The two aspects will match in the sector of energy recovery which appears one of the most powerful tools for fuel consumption saving and CO 2 reduction. When the recovery is done on exhaust gases it has an additional interest, having a moderate cost per unit of CO 2 saved. The potentiality of this recovery is huge: 30%–35% of the chemical energy provided by the fuel is lost with the flue gases. For different reasons engines for passengers cars or goods transportation (light and heavy unit engines) as well those used for electricity generation (gen-set) are interested to this recovery: the first sector for the CO 2 reduction, the second for the increasing value of electrical energy on the market. This wide interest is increasing the probability to have in a near future a reliable technology, being different actors pushing in this direction. In recent years the literature focused the attention to this recovery through a working fluid (organic type) on which the thermal energy is recovered by increasing its enthalpy. Thanks to a sequence of thermodynamic transformations (Rankine or Hirn cycle), mechanical work is produced. Both concept (Organic working fluid used and Rankine Cycle) are addressed as ORC technology. This overall technology has an evident complexity and doesn’t match with the need to keep reduced costs: it needs an energy recovery system at the gas side, an expander, a condenser and a pump. The space required by these components represents a limiting aspect. The variation of the flow rate and temperature of the gas (typical in ICE), as well as that at the condenser, represents additional critical aspect and call for suitable control strategies not yet exploited. In this paper the Authors studied an energy recovery method integrated with the turbocharging system, which does not require a working fluid making the recovery directly on the gas leaving the cylinders. Considering that the enthalpy drop across the turbine is usually higher than that requested by the compressor to boost the intake air, the concept was to consider an additional turbine which operates in parallel to the existing one. Room for recovery is guaranteed if one considers that a correct matching between turbine and compressor is actually done bypassing part of the exhaust gas from the turbine (waste gate) or using a variable geometry turbine (VGT) which, in any case, represents an energy loss. An additional positive feature is that this recovery does not impact on engine performances and the main components which realizes the recovery (valves & turbine) are technologically proven. In order to evaluate the potentiality of such recovery, the Authors developed a theoretical activity which represents the matching between turbocharger and engine. Thanks to an experimental characterization done on an IVECO F1C 16v JTD engine, an overall virtual platform was set up. The result produced a very satisfactory representation of the cited engine in terms of mechanical engine performances, relevant engine flow rates, pressures and temperatures. The ECU functions were represented too, such as boost pressure, EGR rates, rack control of VGT, etc… Two new direct recovery configurations have been conceived and implemented in the engine virtual platform.

The work developed in this paper is realized within the ecoDriver EU FP7 project that is shortly presented in the first part of the paper. Among the several main objectives underlined by this project, one consists in developing a vehicle and energy consumption model to be validated and then used to help the driver to better drive in terms of consumption and safety, advised by a HMI (Human-Machine Interface) module. Several experimental results are shown to illustrate the obtained energy saving with such an EDAS and the legal speed respect.

The depletion of global crude oil reserves, increases in fossil fuel prices and environmental issues have encouraged the search for and study of bio-derived fuels. For years, fatty acid methyl esters (FAME) have already been used successfully. High-quality hydrogenated vegetable oil and Fischer-Tropsch biofuels have also been developed. Fuel refining processes, however, consume energy increasing CO 2 emissions. For profitability reasons, large-scale industrial production is also required. Several distributed energy producers are instead willing to utilize various local waste materials as fuel feedstock. The target is local fuel production without any complicated manufacturing processes. Crude bio-oils are therefore also interesting fuel options, in particular for medium-speed diesel engines capable of burning such bio-oils without any major problems. Nevertheless, waste-derived crude bio-oils have also been studied in Finland in high-speed non-road diesel engines. One option has been mustard seed oil (MSO). Mustard has been cultivated in fallow fields. Non-food mustard seeds have been used for fuel manufacturing. In the performed studies with MSO, the exhaust smoke and HC emissions decreased, NO x remained approximately constant, and the thermal efficiency was competitive compared with operation on ordinary diesel fuel oil (DFO). The number of exhaust particles tended, however, to increase and deposits were formed in the combustion chamber, particularly if the engine was also run at low loads with MSO. On the whole, the results were so promising that deeper analyses of engine operation with MSO were considered reasonable. The kinematic viscosity of crude bio-oils is much higher than that of FAMEs or DFO. Consequently, the injection pressure tends to increase especially at the injection pump side of an in-line injection pump system. The flow characteristics of crude bio-oil also differ from those of DFO in the high-pressure pipe. With bio-oil, the flow seems to be laminar. The bulk modulus of bio-oils is also different from that of DFO affecting the rate of the injection pressure rise. In the present study, a turbocharged, inter-cooled direct-injection non-road diesel engine was driven with a mixture of MSO (95%) and rape seed methyl ester (RME, 5%), and standard DFO. The engine was equipped with an in-line injection pump. First, the injection pressures at pump and injector ends of the high-pressure injection pipe were measured for both fuels as a function of crank angle. Furthermore, a model was created for the injection system based on the method of characteristics. Free software called Scilab was adopted for numerical simulation of the model. Despite a few limitations in the built model, the results showed clear trends and the model can be used to predict changes in the fuel injection process when the fuel is changed.

In order to decrease both energy consumption and CO 2 emissions, the automotive, aeronautics and aerospace industries aim at making lighter vehicles. To achieve this, composite materials provide good opportunities, ensuring high material properties and free definition of geometry. As an example, for cold applications, the use of carbon fiber/thermoset composites is ever increasing, in spite of a high fiber price. But in a global and eco-friendly approach, the major limitation for their use remains their potential recyclability. Recycling a composite means having a recycling technology available, getting a dismantle solution and an access for the product, and disposing identification plus selection possibilities to the materials. Thus, carbon fibers recovery ( i.e. recycling and re-processing) would both help design engineers to balance energy efficiency and cost, and open new opportunities for developing second-life composites, dedicated to the manufacture of medium or low loaded parts (non-structural in many cases). A first section presents an overview of composite recycling possibilities. Indeed, environmentally and economically, composite incineration is not attractive (even with an energetic valorization), let-alone burying. Reuse and recycling thus remain the two most interesting options. Aeronautics offers a high potential in terms of fiber deposit. In southwest France, composites recycling will increase in terms of quantity due to dismantling platforms Tarmac (dedicated to civil aircraft applications) and P2P (for the disassembly of ballistic weapons). In addition, from a technical point of view, and even if end-of-life solutions for composites still remain under development, solvolysis ( i.e. water under supercritical conditions) already offers the opportunity to recover carbon fibers. The resulting recyclate retains up to 90 percent of the fiber’s mechanical properties. A second part will explore the recycling to design issue ( i.e. how recycling processes have to balance the previous aspects of the end-of-life proposal). The recycler clearly becomes a new supplier in the carbon fiber lifecycle, by revalorizing wastes with alternatives to burning. Moreover, increasing carbon fiber shelf life reduces its product life impact. Finally, promoting carbon fiber end-of-life would ensure to link aeronautics, automotive, and leisure and sports industries; but one can create demand for recycled reinforcement, by packaging it in useful and attractive forms for those end-users ( e.g. pseudo-continuous fiber, felt, strips, bands, patches, etc.). These sections will be enlightened by several examples from collaborations between I2M and local industries.

The objective of this work is to analyze and to model the turbulent flames in the context of coherent flame model. We present a detailed description of equations and the flamelet regimes in turbulent premixed flame. A surface density models proposed here represents a good issue for numerical simulation. Extension of coherent flame model and homogenous stilled reactor model is proposed to consider the dynamics behavior of flame and pollutants formation. From the results of this work it is concluded that the coherent flame model allows surpassing difficulties of the turbulent reactive flow modeling. Calculations based on a semi-global kinetic scheme and flamelet formulation combined with a well stirred reactor analysis of the burnt gases are used and provided reasonably accurate values of CO and NO formation. Also, we have observed that CO is formed near the reaction zone (front flame) but emission of CO 2 , H 2 O and NO are formed in the hot gases.

Energy is one of the main cost components in steelmaking operations. For steel industry, there is big pressure of lowering energy consumption and reducing CO 2 emission by energy saving. Decreasing coke rate in blast furnace and increasing amount of liquid steel production per ton of hot metal in basic oxygen furnace (BOF) are the main parameters decreasing energy consumption in an integrated iron and steel plant. In this study, coke consumption and liquid steel production have been predicted through computer simulation of blast furnace and BOF processes. The second law of thermodynamics is very powerful tool in energy optimization of systems. To examine how efficiently energy is consumed in the blast furnace and BOF processes, the following efficiencies have been defined by using second law of thermodynamics: exergetic coke consumption efficiency for blast furnace process and exergetic steel production efficiency for BOF process. Effects of different parameters have been investigated on the energy consumption.

Performance and exhaust emission studies of Waste Chicken Oil Methyl Ester (WCOME)-diesel fuel blends has been presented in this paper. The production of biodiesel from waste chicken oil was carried out via transesterification method. Blending ratios were preferred as 5% (B5), 10% (B10), 25% (B25) and 50% (B50) respectively. Performance and emission studies were carried out in a commercial diesel engine. The performance results reveal that blends of WCOME with diesel fuel provide increase on the brake specific fuel consumption (bsfc) and decrease on the brake power output proportional to the reduction in the heating value of blends. As a result, while the carbon monoxide (CO) and the carbon dioxide (CO2) emissions were reduced, nitrogen oxides (NOx) emissions were stated higher compared with the diesel fuel emission characteristics.

The European Union recently established an ambitious target by 2020 that consists of increasing the utilization of renewable energy up to 20%, reducing its overall pollutant emissions to at least 20%, and achieving a primary energy saving of 20% compared to reported 1990 levels. This aim could be reached only with strong effort in different sectors, such as residential, commercial, industry, tertiary, transportation, .... In particular in the European Union a remarkable contribution to energy consumption and CO 2 emissions is concentrated in residential and commercial sector. The introduction of more efficient technologies in these sectors could help in achieving the results expected by 2020. An option is given by cogeneration, defined as the combined “production” of electric and/or mechanical and thermal energy starting from single energy source, that could be considered one of the first elements to save primary energy, to avoid network losses and to reduce the greenhouse gas emissions. In particular, our interest will be focused on the microcogeneration (electric power ≤ 15 kW), which represents a valid and interesting application for residential and light commercial users. The energetic, economic and environmental implications due to the use of small scale cogeneration systems were reported, starting by an experimental research activity performed by the authors and other researchers.

Exergy analysis provides useful information for the system optimization. An exergy analysis identifies the sources of thermodynamic inefficiencies by evaluating the exergy destruction within each system component. The present work is an attempt to compare the effect of variations of species concentrations of the combustion process in a simple gas turbine system. Therefore, using a Complete combustion model and an Equilibrium combustion program model, the exergetic evaluation is carried out for a simple gas turbine system with a rated output power of 30 MW. The Complete combustion involves O 2 , N 2 , CO 2 , H 2 O and Equilibrium combustion model involves N 2 , O 2 , CO 2 , H 2 O, CO, H 2 , H, O, OH, N, NO as the species of combustion products. In this work, Equilibrium combustion products were calculated using Olikara and Borman method. Also, a principle of division of chemical availability (exergy) into oxidation availability, reduction availability and diffusion availability has been investigated in these models. Expression involving the variables for exergetic efficiency, exergy destruction, and chemical availability in the components of the gas turbine cycle are derived. The exergy losses and efficiencies of components based on both Complete combustion and Equilibrium combustion models are evaluated. The exergetic efficiencies of the plant based on Complete combustion and Equilibrium combustion are determined to be 28.11% and 28.16%, respectively. It is found that, variation of species has negligible effect on the system main parameters. It is also concluded that chemical exergy in Equilibrium combustion is a little more than that of Complete combustion. Because of additional species involved in Equilibrium combustion, reduction availability and oxidation availability are defined in this modeling beside diffusion availability and it increases chemical exergy of equilibrium combustion modeling. The results obtained here show that in the analysis of the power plant cycles, a simple combustion model (i.e. Complete combustion model) is in good agreement with a complex combustion model considering various species (i.e. Equilibrium combustion model). As a result, there is negligible difference between results of the mentioned combustion models and the simple Complete combustion model facilitates the analysis of such processes.

Geothermal heat pumps with ground source heat exchangers have been widely used for heating and cooling homes as well as for domestic water heating. A study on a small house in Erbil-Iraq was conducted to assess energy savings when using GHPs with closed loop ground source heat exchangers as compared with air-to-air heat pumps. Local climate conditions and soil properties of Erbil located in the north of Iraq were used. The simulation was performed using TRNSYS-16 software. The results of this study show that we can reduce the energy used for heating and cooling by 39% during annual when using GHP. The simulation also showed that the average COP for heating is 2.9 and for cooling is 2.6 when using air to air heat pumps and the average COP for heating is 5.6 and 3.6 for cooling when using GHP. This reduction in energy reduces the CO 2 emission as it reduces energy consumption.

Indoor air quality (IAQ) is nowadays universally recognized as an important issue that affects the comfort and health of people, as well as their productivity. This paper describes the relationship of indoor CO 2 concentration to building air quality and ventilation, with a focus on how CO 2 can be used to evaluate and predict air quality and ventilation performance, namely the infiltration airflow rate. Besides it shows the ability of ESP-r building simulation software for predicting the CO 2 concentration and the air exchange rate in a building. For this purposes a room of a hotel located in the urban area of Coimbra was chosen. The developed simulation model was then validated against empirical results. It was shown that a fair degree of agreement between ESP-r results and the experimental observation exist for the zones. High accuracy of the simulation model showed that building simulation software, namely ESP-r can provide a better understanding of indoor environmental conditions and be a powerful tool in finding the best modification measures for improving the indoor air quality in a building.

Concerns about the effect of CO 2 emissions on climate change and rising energy costs have renewed the interest in efficiency improvement in fossil fuel use as well as the utilization of locally available low or moderate temperature heat sources, such as geothermal or solar. This paper summarizes twenty years of Ormat’s very significant achievements in developing cycles, configurations and equipment for electricity generation from low grade waste heat and water dominated geothermal resources. As of the end of 2007 some 30 plants ranging from 200 kW to 130 MW totaling about 1000 MW are in operation.

In the present study, the effects of inlet jet geometry on the process of mixture with variable density have been investigated numerically. Three density ratios were considered, namely 1.0, 1.8 and 0.66 for Air-air, CH4-Air and CO2-Air mixtures respectively. The jets are produced through rectangular, elliptic and triangular tubes with aspect ratio 1.33. A second-order Reynolds stress model (RSM) is used to investigate variable density effects in asymmetric turbulent jets. Comparative studies are presented in the case of the calculations of the average variables such as the longitudinal velocity, species and the turbulent kinetic energy. The results obtained show that the asymmetric geometry noticeably enhances mixture in comparison with the axisymmetric case. Typical phenomenon of 3D jets are observed.