Renewable energy has a significant role to play in helping the world achieve the greenhouse gas emission reduction necessary to achieve the pathway to a 2°C increase in global temperature. Electricity generation from wind and solar resources can contribute immensely to the decarbonization of power generation, but these resources are intermittent. High penetration of intermittent renewable power generation can cause grid stability and control issues for network operators, with fast response fossil fuel power plant necessary to provide security of supply and maintain grid stability. Increasingly natural gas-fueled distributed power generation is being installed to provide the necessary grid support. However, hybrid power plants comprised of a fossil fuel power generating system, a renewable power generation system and energy storage can provide both the low CO 2 electricity required to meet environmental constraints, and the despatchability and stability required by grid operators. Integrated Solar Combined Cycle Power Plants (ISCCs), comprising a Concentrated Solar Power plant and a natural gas fired combined cycle plant, have the potential to simultaneously reduce fossil fuel consumption, provide secure, highly predictable electricity generation, and reduce the cost of integrating renewable energy into a power system. While a number of ISCCs have been built at a larger scale (above 150MW power output), the concept has rarely been adopted for smaller scale distributed power applications. In addition, the traditional ISCC concept uses a steam bottoming cycle, which consumes water, and often locations where distributed ISCC could be utilized suffer from a scarcity of fresh water. This paper evaluates whether replacing the steam bottoming cycle with an Organic Rankine Cycle (ORC) alternative can provide a simpler, lower cost distributed ISCC solution that can be utilized on smaller and island grid systems, or mini- and micro-grids, to provide an affordable, water-free, low carbon power generation system.

The small solar thermal power plant is being developed with funding from EU Horizon 2020 Program. The plant is configured around a 2-kWel Organic Rankine Cycle turbine and solar field, made of Fresnel mirrors. The solar field is used to heat thermal oil to the temperature of about 240 °C. This thermal energy is used to run the Organic Rankine Cycle turbine and the heat rejected in its condenser (about 18-kWth) is utilized for hot water production and living space heating. The plant is equipped with a latent heat thermal storage to extend its operation by about 4 hours during the evening building occupancy period. The phase change material used is Solar salt with the melting/solidification point at about 220 °C. The total mass of the PCM is about 3,800 kg and the thermal storage capacity is about 100 kWh. The operation of the plant is monitored by a central controller unit. The main components of the plant are being manufactured and laboratory tested with the aim to assemble the plant at the demonstration site, located in Catalonia, Spain. At the first stage of investigations the ORC turbine will be directly integrated with the solar filed to evaluate their joint performance. During the second stage of tests, the Latent Heat Thermal Storage will be incorporated into the plant and its performance during the charging and discharging processes will be investigated. It is planned that the continuous filed tests of the whole plant will be performed during the 2018–2019 period.

Historically, combustion modeling is important for many transportation- and ground-based applications. More recently, modeling has been offered as an early screening tool in the evaluation of a potential alternative aviation jet fuel. This combustion evaluation path would in theory be conducted by gas turbine Original Equipment Manufacturers (OEMs) on proprietary geometries and conditions. Ideally, OEMs would have access to the latest combustion theory models and would thus have the highest predictive confidence in their model predictions. Unfortunately, the latest combustion theory codes are not written for commercial purposes. This work identifies and develops a conduit for OEM usage of latest flamelet theory for use in the evaluation of alternative jet fuel combustion properties. A so-called “common format routine” (CFR) software with two low-dimensional manifold combustion models that can be used for laminar and turbulent applications is developed, which can be implemented by OEMs on proprietary hardware. The two models are the flamelet prolongation of the intrinsic low-dimensional manifold (FPI), used for premixed combustion, and the flamelet progress variable (FPV), utilized for nonpremixed combustion. The three branches of combustion are computed using a hybrid tool that combines homotopic flamelet calculations with scaling laws and the two- and one-point flamelet continuation methods in order to resolve bifurcations. The mixture fraction and progress variable definitions can be chosen to be any summation of atomic and species composition, respectively. Diffusivity coefficients can be computed using unity Lewis number, mixture-averaged and multicomponent species composition. The turbulence-chemistry interaction is tabulated a priori using Beta probability density function (PDF) for the mixture fraction and Beta or Dirac-delta PDF for the progress variable. Parallel computing is necessary for industrial quality tabulation. The tabulated table can be used for k-ε and k-ω RANS, SAS, DES, and LES simulations. The software can also interact with liquid spray and exchange mass between the liquid and gaseous phase. The software is verified against previous numerical simulations of canonical triple flames, piloted flames and single-cup combustor. The numerical results are validated against experimental measurements of temperature and species mass fractions. The CFR software advances Cantera 2.3. Hence, the software contains an inner layer of C++ code, an intermediate layer of Python wrappers, and an upper layer (GUI) of C# code. The pre-tabulated chemistry is used for CFD simulations. The tables are bi-linearly interpolated for laminar simulations and tri-linearly interpolated for turbulent simulations. The tabulated chemistry can be hooked to commercial software such as Fluent through C and Scheme codes. The simulated flames presented here were computed with this software. The developed software is reliable for modeling and simulation of complex combustion phenomena.

Totally enclosed air to air cooled (TEAAC) generator with IC6A1A6 (as per IEC 60034-6) cooling is a widely accepted generator cooling solution for squirrel cage induction generators (SCIG) used in wind power generation, where the generator has two cooling systems, internal and external. The internal cooling is a closed loop system, where a shaft mounted mechanical fan helps in recirculating air inside the generator, and transfers the heat from the generator into an air-to-air heat exchanger. The external cooling system is a separate ventilation system creating airflow from the nacelle through the heat exchanger and removing the heat outside the nacelle with the help of an electrical fan mounted near the non-drive end of the generator. Cooling improvement of generator and bearing windings for performance enhancement is a well known research topic in turbo-generation as well as wind energy. Various winding design effort has been made in past for efficient generator cooling for turbogenerator as well as for wind turbine generator. With the increasing demand of power output, winding and bearing temperature class reaching its limit. Challenge is to come up with a solution for improving the performance of generator in terms of reducing temperature experienced by windings and at the same time reducing the cost. Detailed testing has been done on a test turbine to compare results obtained from open ventilated solution IC3A1 (as per IEC60034-6) and IC6A1A6 cooling for the squirrel cage induction generator. Paper presents advantages in case of using IC3A1 cooling where temperature of windings reduced substantially in comparison with IC6A1A6 cooling. To avoid contamination led windings and bearings hotspots, presented IC3A1 cooling configuration uses a unique design with inlet duct, filters, outlet duct and wire mesh.

In order to pursue superior cycle efficiency and lower power generation cost for the CSP plants, two S-CO 2 –Brayton–cycle–based power cycles with different utilization methods of the residual heat recover of the top S-CO 2 Brayton cycle (SCBC) are investigated to seek alternatives to the stand-alone S-CO 2 cycle as the power block of concentrated solar power plants. The residual heat released by the top S-CO 2 cycle are either utilized to drive a LiBr absorption chiller (AC) for further chilling of the CO 2 fluids exiting the precooler before entering the main compressor inlet temperature or recovered by an organic rankine cycle (ORC) for generating electricity. Thermo-economic analysis and optimization are performed for the SCBC–AC and SCBC–ORC, respectively. The results show that the thermal and exergetic efficiencies of the SCBC–AC are comparable with those of the SCBC–ORC in low pressure ratio conditions ( PR <2.7) but are apparently lower than SCBC–ORC when PR is over 2.7. The LCOE of the CSP plant integrated with SCBC–AC is more sensitive to the change of PR . The optimal PR to maximum the cycle efficiency or minimize the plant LCOE for the SCBC–ORC is higher than that for the SCBC–AC, while the optimal recuperator effectiveness to minimize the LCOE of CSP plant integrated with SCBC–ORC is lower than that of SCBC–AC. The optimization results show that the thermo-economic performance of the SCBC–AC is comparable to that of the SCBC–ORC. Significant η ex improvement and LCOE reduction can be obtained by both the two combined cycles relative to the stand-alone S-CO 2 cycle. The maximal η ex improvements obtained by the SCBC–ORC and SCBC–AC are 6.83% and 4.12%, respectively. The maximal LCOE reduction obtained by the SCBC-ORC and SCBC–AC are 0.70 ȼ / (kW·h) and 0.60 ȼ / (kW·h), respectively.

Large eddy simulation/Flamelet progress variable approach is employed in current research to investigate how flame behaviour is influenced by bluff-body and coflow composition. We used Sydney bluff-body burner as the target burner. Computation grid in cylinder coordinates is approximately 2.7 million in total number, extended to the downstream location 80 times of jet diameter. Three coflow compositions with different oxygen ratio at the same inlet velocity are considered. Comparing to jet flames with hot and diluted coflow, instantaneous and statistical results showed that an introduction of bluff-body preheats the fuel and shortens the flame length. At lower oxygen ratio condition, a weaker reaction zone emerged, marked by lower temperature and OH concentration; the flame appeared lifted gradually, leading to a potential MILD combustion. Besides, bluff-body effect behaves differently in these flames: at lower oxygen ratio condition, a large-scale distribution of CH2O appeared as a marker of partial premixing and preignition reaction in recirculation area; on the contrary, in higher oxygen ratio case, the recirculation area brings out more reactive fuel at lower speed and higher temperature, hence ignitable in the vicinity of bluff-body.

Development of alternative, clean and renewable energy production from different hydrocarbon materials helps to partially replace the limited resources of fossil fuels and also help reduce carbon emissions from fossil fuels that drives global warming. Biomass and bio-wastes are renewable and sustainable hydrocarbon resources, which can be used for energy and fuels production along with permanent disposal of plastic wastes. Landfills of wastes is unsustainable with additional problems of non-degradability and growing burden to the environment and society. Co-pyrolysis and co-gasification of biomass with different types of plastic wastes has shown to provide enhanced product yields and quality for syngas and liquid fuel production. To date, limited information is available on the understanding of chars produced from co-pyrolysis. The effect of co-pyrolysis on the type, quality and yield of chars produced is essential for efficient utilization of a wide variety of biomass, bio-waste and plastic waste resources. This paper provides information on the effect of plastic addition to the pyrolysis of biomass as well as the quality and quantity of char produced with different amounts of plastic waste added at different pyrolysis temperatures. TGA reactor was used for all these investigations and the quality of char produced was examined from the perspective of char combustion for energy production. Char is commonly produced as a by-product from pyrolysis and gasification reactors. Carbonization temperatures investigated were in the range of 573–773 K for 30 min using pinewood biomass, while recycled polyethylene terephthalate was used as plastic waste. The investigations revealed that chars produced from co-pyrolysis especially for carbonization temperature (T c ) of 673 K and above behaved completely differently than the chars produced from separate pyrolysis of biomass and plastic waste under the same pyrolysis conditions. These chars produced from co-pyrolysis were more uniform in their behavior in oxidation environment, with higher heat flow for almost similar quantities of chars during oxidation. This was conjectured to be from enhanced quality of chars produced having increased C content (from increased heavy aromatics and efficient loss of volatiles) during co-pyrolysis without any loss of char yield. The char yield was found to be equal or higher during co-pyrolysis compared to the weighted aggregate of individual pyrolysis. These investigations provided novel results on the behavior and capabilities of chars produced from co-pyrolysis of biomass and plastic wastes to provide a new avenue for the quality enhancement of bio-chars and efficient utilization of carbonaceous solid waste resources.

A shell and tube heat storage (1 MJ) has been designed computationally to enhance the heat transfer rate from heat transfer fluid (HTF) to the storage media. Concrete and water are considered as the sensible storage material and HTF, respectively. The system can be used to store the solar energy in the day time, which will be available in the absence of sunlight. Finite element based software, named COMSOL Multiphysics, is used for the study. The parameters analyzed, are tube outside diameter, radial distances between the tubes, number of tubes and inlet temperature of HTF. After a simulation time of 3000s, the increase of tube diameter from 1.03 to 1.71 cm is found to increase the average storage bed temperature by 6.3%. For the radial distances between the tubes to be 6 cm, the stored energy is maximum. The stored energies for 5 and 4 cm are 2.4 and 12.4% less than 6 cm, respectively, after duration of 6000s. The average bed temperature reaches to the steady state condition at 5147s with 19 tubes, whereas, with 25 tubes it takes 30.2% less time. Finally, the shell and tube heat storage has been optimized for higher heat transfer rate.

With the everlasting increase in the population, a huge surge in the electricity consumption can be noticed. Thus, the power and electricity generating power plants need to augment their performance to cope with this uprising problem. The main goal for most gas turbine power plants is to increase their efficiency and performance which can be achieved by increasing the turbine inlet temperature (TIT). However, increasing the TIT requires cooling of the turbine blades to extend its lifetime and avoid thermal stresses and oxidation rates. Usually, there are two routes to improve the turbine blade cooling, either scientist focus on the parameters that effect the cooling process such as the film cooling effectiveness, shape of holes and angle of injection, or the problem is approached from a thermodynamic point of view. It is well known that the air used to cool the turbine blades is bled from the compressor which causes a severe penalty on the thermodynamic efficiency and power output of the gas turbine. This paper main objective is to improve the gas turbine performance by lowering the temperature of the coolant lines bled from the compressor for turbine blade cooling resulting in a reduction in the amount of coolant mass flow rate required for turbine cooling which will reduce the penalty on the overall efficiency increasing it. For this purpose, three different configurations of Maisotsenko desiccant cooling systems were proposed to cool down coolant lines as well as the inlet air temperature. Optimization analysis was performed to determine the best operating parameters of the gas turbine as well as the cooling systems. Sensitivity analysis was conducted as well to investigate the effect of various variables on the gas turbine overall efficiency and the coolant mass flow rate. The results showed an increase in the overall efficiency from 42.57% to 43.83%, reduction in the amount of coolant mass flow rate that is bled from the compressor from 4.584 kg/s to 3.607 kg/s and in the cooling fraction from 4.72% to 3.9%.

Renewable energy is one of the most promising solutions to energy shortage that may occur in the future particularly in remote areas. Solar cells suffer from the problem of high temperature, which reduces the electrical efficiency and operational life. In this study we investigate a new hybrid technique of cooling and voltage induction. A set of small generators installed on the back of a solar panel operating under the influence of heat and magnetic energy are called thermo-magneto-electric generators (TMEG). A modeling study was done using COMSOL Multiphysics5.2a (COMSOL) software as a package to simulate the physical states of the system. This study showed that a TMEG has the ability to improve the efficiency as a result of reducing the temperature. An induction voltage is also an output of the system and can be combined with the output of the solar panel composing the hybrid system.

The traditional organic Rankine cycle (ORC) is operated below critical point. However, the specific heat of the working fluid undergoes tremendous change near the critical point. This can improve the thermal performance of the system due to the enhancement of heat transfer coefficient within the heat exchanger. However, the strong temperature dependence of thermo-physical properties of the working fluid especially at near the critical point requires much more efforts in designing a heat exchanger. Hence, more elaborate calculation involving stepwise integration is needed as far as accuracy is concerned. Therefore the heat exchanger is divided into several segments. The outlet temperatures of the first segment serve as the input parameters for the second segment, and the process is carried out further on. The fluid properties are calculated with the actual bulk temperature of each segment. With increasing number of segments, better resolution of temperature distribution of both heat source and working fluid within the heat exchanger is achieved. In the present study, a plate heat exchanger was numerically examined by using R-245fa as a working fluid at a supercritical condition. The effects of the working pressure and mass flow rate were examined in detail. For all cases in this study, the maximum of the total heat transfer rate was achieved by a working pressure of 3700 kPa, especially close to critical pressure. It is found that at a working pressure of 4000 kPa and mass flow rate ranging from 1 kg/s to 1.75 kg/s, the total heat transfer rate was independent of the mass flow rate.

Traditionally, water is used in thermal power plant for heat rejection processes such as in the steam condenser for use in a Rankine cycle. Typically, research has shown that approximately 2 litres of water are required to generate 1 kWh of electricity on a wet-cooling system; which on a bigger scale could translated to more than 11000000 m 3 per year of make-up water for a 600 MWe coal-fired plant. The ever-increasing cost of water resources as well as the water resource scarcity have paved a path to dry-cooling systems which alternatively provide a significant cooling potential. However, dry-cooling systems performance are generally driven by the atmospheric conditions which at time do not meet the desired cooling temperatures resulting in significant drop in their performance. Recent developments in cooling technology suggest that hybrid systems (dry-wet) be used to insure good and manageable performances while maintaining the cost of operation at admissible range. In light of the recent draught experienced in South Africa, attention was drawn to evaluation of deluged systems performance as well as water consumption to increase the public awareness in the field. In this study, a deluged bundle was used to experimentally determine the cooling performance characteristic as well as water consumption for performance management. The above is then considered on a bigger scale to in order to open floor for further discussion on future strategies in term of the South African policy on water usage.

In this paper, a novel nodalized reduced order model (NROM) has been developed to analyze the linear stability in a heated channel using supercritical water (SCW) as a coolant. The presented reduced order model is developed based on the two-phase flow system approach. The model is much simplified, which reduced the requirement of computational efforts and resources. In the heated channel, the SCW’s density shows a dramatic downfall near the pseudo-critical temperature, based on which it has been divided into n number of nodes. The one-dimension partial differentiation conservation equations of energy, mass and momentum are used and have been linearized by a small perturbation applied on its steady-state solution. These PDEs are converted into the corresponding time-dependent, nonlinear ordinary differential equations (ODEs) by using weighted residual method applied under some appropriate assumptions and approximations. These sets of ODEs (n+1 equations) are then solved analytically by using a state space approach to capture the stability boundary (SB) in terms of trans-pseudo-critical phase change number ( N tpc ), pseudo-subcooling number ( N spc ) by applying a constant external pressure drop (Δ P tpc ) condition across the channel. The NROM results are found to be in good agreement with the methodology and have been verified by numerical simulation. To extend this as a nonlinear stability analysis, the different types of the Hopf Bifurcation regime are also reported.

Nitrogen oxide (NO x ) emitted from boilers in coal-fired power plant may be reduced by 90 percent through the application of the selective catalytic reduction (SCR). However, the escaped ammonia from the SCR systems could react with sulfur oxides (SO x ) in the flue gas to form ammonium bisulfate (ABS) in exhaust systems. The blockage and corrosion caused by ABS seriously impact the rotary air preheater (RAPH), which would not only increase operating cost on ash-blowing and cleaning but also lead to unplanned outage. To solve the problem, in this paper a novel preheater system is proposed. A single preheater is split into two sub-preheaters, between which the main flue gas flow is mixed with the recirculated flue gas from outlet of the lower-temperature preheater. After the mixing point, a reaction chamber and a precipitator are installed. A numerical finite difference method (FDM) is employed to model the RAPH and obtain the accurate temperature distribution of fluid and heat transfer elements. The initial formation temperatures of (NH 4 ) 2 SO 4 and ABS are 200 °C and 170 °C, respectively, according to the flue gas composition in this work. By calculation, this split design of the RAPH is believed to be effective in reducing deposition of ABS.

A series of experiments were performed on a vertical EV burner with a constant coflow air of 873 L /min to generate turbulent lean premixed flow in order to study the impact of the addition of Acetylene/Argon mixture to the liquefied petroleum gas (LPG) on the temperature field and flame structure. The fluidics mechanism was inserted at a fixed position inside the entry section of the EV burner assembly. The flow rates of fuel (LPG/C 2 H 2 / Ar) and air were measured using calibrated rotameters. The different volume ratios of the fuel constituents (at a specified fuel flow rate) were admitted via three solenoid valves at the entry section of each stream prior to mixing and monitored using a labview program. The axial temperature profiles at different operating conditions were measured using a bare wire Pt-Pt -10% Rh (type S) thermocouple of wire diameter 250 μm. Flame images were obtained — before and after fluidics insertion — using a high resolution Canon 6D 20MP digital camera. The selection of the different considerated cases was based on flame stability. The experimental program aims at identifying and analyzing the changes in flame characteristics (flame length, axial profiles of mean gas temperature, NOx concentration and overall combustion efficiency) resulting from the insertion of fluidics while considering different proportions of the fuel constituents) (including pure LPG, as a reference case). In all experiments flame stabilization was ensured. The results obtained indicate the following: it was noticed that in most cases of pure LPG only, and other mixtures the images shows increase in both the length and luminosity of the flame as a result of higher degrees of swirl due to the fluidics insertion while the temperature profiles of the different flames were changed. It was indicated that NOx trend was decreased by 52% while the combustion efficiency was improved by 2.5%.

High-temperature Gas-cooled Reactor Pebble-bed Module (HTR-PM) is under construction in Shidao Bay, Shandong of China. It is supposed to be the world’s first pebble-bed modular commercial demonstration plant for High Temperature Gas-cooled Reactor (HTGR). In HTR-PM project, water-Rankine cycles have been used in the power conversion system. Meanwhile, supercritical carbon dioxide (S-CO2) Brayton cycle has shown great potentials for future HTGR technology. Comparing with typical helium Brayton cycle, in S-CO2 cycle where critical properties of carbon dioxide are utilized, compressor work may reduce significantly and thermal efficiency may improve greatly. Furthermore, the general sizes of S-CO2 cycle equipment, such as heat exchanger and turbine, would be orders of magnitude smaller than water-Rankine system at similar power output. Therefore, parameters study of S-CO2 were conducted in this paper for future HTGR. Firstly, a physical model of S-CO2 Brayton cycles was built and the performance of cycles were analyzed. Secondly, compression ratio, temperature ratio, the inlet temperature of turbine, inlet parameters of compressor, and recuperated effectiveness were discussed as key cycle parameters. For heat capacities of CO2 are significantly different as a function of temperature and pressure, flow recompression was considered. Calculation was based on a split-flow cycle configuration. The split flow ratio was also analyzed. Finally, the parameters of S-CO2 cycle were optimized for HTGR. In conclusion, S-CO2 Brayton cycle will be a good option for future HTGR.

Experimental study of a swirl flow using 3-D Stereo-PIV (Particle Image Velocimetry) that models a gas turbine blade internal cooling configuration is presented. The work is intended to provide an understanding of the advancements of swirl cooling flow methodology utilizing 3-D Stereo-PIV. The study aims at determining the critical swirl number that has the potential to deliver the maximum heat transfer results. In the swirl cooling flow methodology, cooling air is routed to the turbine blades where it passes through the blade’s internal passages lowering the temperature. An experimental setup with seven discrete tangential jets at three different Reynolds numbers is designed to allow detail measurements of the flow. To provide the particles for velocity measurements an oil particle seeder (LAVision) is used. The circular chamber is made of clear acrylic to allow visualization of the flow phenomena. Data is post-processed in DaVis, velocity calculations are conducted in MATLAB, and TechPlot is used for data visualization. This investigation focuses on the continuous swirl flow that must be maintained via continuous injection of tangential flow, where swirl flow is generated with seven inlets and decays with downstream distance. It was also determined that the critical swirl number, S n , depends greatly on the location and size of the tangential slots.

In previous references, no study has been done on the optimization of rotary regenerative air preheaters (RAPHs) used in coal-fired power plants yet. The key structure parameters of RAPH include rotor radius, fluid section angles and matrix layer heights. In this study, work on the multi-objective design optimization of an RAPH was conducted by combing the thermal hydraulic calculation program which is developed to calculate the temperature and the pressure drop and the non-dominated sorting genetic algorithm (NSGA-II). The maximum heat transfer rate and the minimum friction, namely minimum outlet gas temperature and pressure drop, are considered as the conflicting objectives in the multi-optimization. The layer heights, rotor radius, angles of fluid sections and heights of matrix layers are involved in the design variables in the optimization. The optimization includes three cases in which the rotor radius upper limits are 7 m, 8 m and 9 m respectively. Sets of the Pareto-optimal front points were obtained for the different cases. The obtained optimal air-preheaters with larger upper limit of rotor radius would have better Pareto results. The optimum rotor radius is the upper limit value for different design range of rotor radius. The air-preheaters with larger upper design limit of rotor radius would have better Pareto results. In other words, if the upper design limit of rotor radius is too small, all the Pareto points in this case could not satisfy the performance requirements of heat transfer and friction, and the only way is to increase the upper design limit of rotor radius. The ratio of each optimum fluid section angle is determined by the fluid flow rate of each section.

Scarcity and restrictions in the use of cooling water has prompted power plant developers to explore multiple sources of cooling mediums to condense turbine exhaust steam in a steam surface condenser. The cooling mediums can have different chemistries dictating selection of different tube and tubesheet materials. The flowrate, inlet temperature and temperature rise for the cooling mediums can be different. Some cooling mediums may not be available during certain times of the year. The resulting steam surface condenser will include multiple smaller tube bundles of various sizes operating with different flowrates and temperatures. The challenges in designing a condenser that employs multiple sources of cooling medium with different chemistries, flowrates and inlet temperatures are enormous. To ensure reliable operation a number of thermal, hydraulic and mechanical design issues must be carefully evaluated. Determining performance of the entire condenser at off-design conditions with variations in flowrates and inlet temperatures of one or more cooling water streams (or absence thereof) can be complicated. This paper highlights the major concepts that need to be addressed while designing a steam surface condenser that employs multiple sources of cooling medium to condense the turbine exhaust steam. Critical thermal, hydraulic and mechanical design issues that can impact the performance and reliability of the overall condenser are addressed.

Power and freshwater demand are increasing as populations around the world keep growing. Due to the environmental impact of using fossil fuels and limited resources, using solar thermal in desalination application is a valuable option. In this paper, an innovative new design of low temperature multi-effect desalination coupled with mechanical vapor compression (LT-MED-MVC) powered by supercritical organic Rankine cycle utilizing a low-grade solar heat source using evacuated tube collectors is analyzed. The proposed design has the potential to desalinate water of high salt concentrations or brine with high salinity more than 100,000 ppm or effluent streams from a power plant with low energy consumption and high efficiency when compared to the previously discussed systems. The performance of the LT-MED-MVC was found to be better than similar systems found in the literature. The specific power consumption for MVC is lower than 4 kWh/m 3 for seawater feed salinity of 100,000 ppm, 14 forward feed effects, and a recovery rate of 50%. The overall system efficiency is about 14%. The impact of increasing the number of effects, motive steam temperature, pressure of supercritical-ORC and salt concentration on the specific power consumption, solar collector area, and the system efficiency are also analyzed.