Net Head Research Articles

Local Area Development through Hydropower Project: A Case Study of Parbati Hydro-electric Project Stage-III (520MW) in Kullu District of Himachal Pradesh India

Hydropower is considered as renewable, cheap and pollution free source of energy in comparison to conventional source of energy. The major river system and topographical variation in Indian Himalayan Region(IHR) offer huge hydroelectric potential because of available net head and water discharge. Efforts are being made for sustainable harnessing of hydroelectric potential of IHR to meet the gap between demand and supply of electricity. Most of these hydropower sites are located in remote hilly terrain of IHR with limited infrastructure like access road, market, hospital etc. For timely execution of hydro power projects(HPPs), infrastructure development is required by project proponent at a faster pace. Like any other developmental projects, establishing of HPPs are also associated with some pros and cons however, the benefits of hydro-projects in terms of infrastructure facility such as road, bridge for proper connectivity, job prospects in construction works, market, civic facilities, source of cheap and clean electricity play a pivotal role in socio-economic development of particular region and nation as well.Present study has been conducted for Parbati Hydroelectric Project Stage-III (520MW) constructed on river Sainj in Kullu district of Himachal Pradesh, India. All the Project components are located in Sainj valley of Kullu district, a part of Beas basin in North-western Himalaya. The objective of study is to assess and evaluate the Local area development (LAD) in Sainj valley following the start of construction of Parbati HE Project-III in the Year 2006 by NHPC Limited (a Government of India Enterprise-miniratna). The assessment of local area development is based on comparison of baseline data of Sainj area prior to start of construction of project and data available during construction phase of project followed by reviewing of Govt. policy for Local Area Development Fund (LADF) in project affected area and consultation with people from project affected gram-panchayats located in the vicinity of construction sites to know their perception about the role of Parbati hydroelectric Project Stage-III in local area development of Sainj valley. The result of study shows that there is substantial increase in developmental activities in and around the project area due to the construction of Parbati HE Project-III. Particularly, infrastructural development (road-bridge) led to improvement in communication and accessibility of villages (Manham, Banau, Sapangini,Talara) in Sainj valley, better transport facility for horticulture products of farmers in Sainj valley to nearby market located on NH-21. The prospects of job opportunities in Project construction works, ancillary activities and in petty contract works also improved. Implementation of community development Schemes of NHPC led to availability of additional medical facilities, educational facility in Govt. Schools and development of socio-cultural aspects (Crematorium, melaground, toilets,watersupply etc) in Sainj valley are attributed to the construction of Parbati HEP-III. During construction phase of the project, in compliance to Govt. policy for LADF @ 1.5% of project cost allocated for execution of developmental works resulted in source of specific fund for development opportunity in Project affected area(PAA) in the valley and nearby areas. Out of total LADF for PAA, 60% was shared equally among three project affected gram-panchayats and remaining 40% among 04 gram-panchayats for taking-up developmental works by resolution of Gram-Shaba and local area development Committee(LADC). Also, during operational phase of Project, the provision of LADF @ 1% share of free power and revenue equivalent to 12% share of free power to State Govt. of Himachal Pradesh from Parbati HEP-III on annual basis through-out the life span of project are continuous source of financial gain from Parbati HEP-III which will act as a stimulus for development.

Efficiency of bio- and socio-inspired optimization algorithms for axial turbomachinery design

Turbomachinery design is a complex problem which requires a lot of experience. The procedure may be speed up by the development of new numerical tools and optimization techniques. The latter rely on the parameterization of the geometry, a model to assess the performance of a given geometry and the definition of an objective functions and constraints to compare solutions. In order to improve the reference machine performance, two formulations including the off-design have been developed. The first one is the maximization of the total nominal efficiency. The second one consists to maximize the operation area under the efficiency curve. In this paper five optimization methods have been assessed for axial pump design: Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Cuckoo Search (CS), Teaching Learning Based Optimization (TLBO) and Sequential Linear Programming (SLP). Four non-intrusive methods and the latter intrusive. Given an identical design point and set of constraints, each method proposed an optimized geometry. Their computing time, the optimized geometry and its performances (flow rate, head (H), efficiency (η), net pressure suction head (NPSH) and power) are compared. Although all methods would converge to similar results and geometry, it is not the case when increasing the range and number of constraints. The discrepancy in geometries and the variety of results are presented and discussed. The computational fluid dynamics (CFD) is used to validate the reference and optimized machines performances in two main formulations. The most adapted approach is compared with some existing approaches in literature.

CFD Analyses and Experiments in a PAT Modeling: Pressure Variation and System Efficiency

Analysis of a PAT modeling is presented for application in water pipe systems as an interesting and promising energy converter to improve the system energy efficiency. The study is focused on the use of a Computational Fluid Dynamics (CFD) model in conjunction with laboratory data for representing PAT performance. The first stage of the procedure concerns a systematic analysis of the role played by the characteristic PAT parameters in the computational mesh definitions of the CFD model, with the aim of defining the most efficient set of capturing the main features of the PAT behaviour under different operating conditions. In the second stage, comparisons of CFD results and experiments were carried out to examine some system components for better understanding the PAT response. Specifically, the behavior of the pressure distribution along the PAT installation when implemented in a water pipe system are analyzed, and the links between pressure variation and the head drop in different system components responsible for the head losses and net head definition are also examined.

PATs selection towards sustainability in irrigation networks: Simulated annealing as a water management tool

Abstract Irrigation networks involve many water and energy aspects, in which the sustainability plays a paramount role. Nowadays, water tariff in irrigation networks represents a high percentage within of farmers' costs, partially due to the low hydraulic and energy efficiency. The installation of pumps working as turbines enables to reduce the pressure and it makes possible the energy generation. In this research, a new maximization methodology to recover energy, considering the feasibility of the installation, was proposed to allocate PATs within networks. Simulated annealing techniques were used with different objective functions as well as different number of machines. Once the maximum energy lines were defined, real machines were selected through the discharge and the head number, considering the available net head in each allocation. Furthermore, the use of WaterGEMS® software enabled to simulate the flow, the pressure and the efficiency variation in the installed machine over time. The combined use of WaterGEMS® and the simulated annealing in the proposed methodology is a powerful water management tool towards the search of the sustainability in irrigation networks. To illustrate the proposed methodology, a case study was presented, obtaining a recovered energy of 26.51 MW h/year (10% of the provided energy in the network).

Experimental study of operation performance for hydrocarbon fuel pump with low specific speed

In this paper, a small flow rate hydrocarbon turbine pump was used to pressurize the fuel supply system of scramjet engine. Some experiments were carried out to investigate the characteristics of turbine pump driven by nitrogen or combustion gas under different operating conditions. A experimental database with regard to the curves of the rotational speed, mass flow rate and net head with regard to centrifugal pump were plotted. These curves were represented as functions of the pressure and temperature at turbine inlet/outlet and the throttle diameter at downstream of centrifugal pump. A sensitivity study has been carried out based on design of experiments. The experimental was employed to analyze net head of centrifugal and throttle characteristics. The research results can accumulate foundations for the close loop control system of turbine pump.

Experimental Investigation of the Influence of Penstock Configuration and Angle of Twist of Flat Blades on the Performance of a Simplified Pico-Hydro System

The effects of penstock configuration and lateral twist angle of the flat blades on the performance of a simplified Pico hydro system were examined as part of an ongoing development. Two configurations of the penstock having 2 and 1 stages of area reductions from 3 to 2 inches and 3 to 2 inches within the lower 1 m of their total height were used. Turbine runners with flat blades laterally twisted at angles of 30, 45, 60, 75 and 90° were fabricated locally and the system performance studied. The speed of rotation of the alternator and turbine shafts were measured and the available fluid power, flow rate and net head were computed. The results show that the 90° blade twist gave the best performance of the simplified system in terms of rotational speed and consequently power for both penstock configurations while the 30° twist yielded the least values of the parameters. However, the respective values for the 1st configuration were relatively higher for all the twist angles used. The maximum values of the parameters obtained for the 2-stage area reduction were 1844.7 rpm and 3636 W while the corresponding values for the other configuration were 1810.6 rpm and 2422 W The simplicity of the flat blade configuration coupled with the system performance for the entire blade twist angles indicates good promise for the implementation of the system for generation of clean, decentralized energy in line with current global trends even in locations without naturally flowing water.

Experimental Investigation of the Influence of Penstock Configuration and Angle of Twist of Flat Blades on the Performance of a Simplified Pico-Hydro System

The effects of penstock configuration and lateral twist angle of the flat blades on the performance of a simplified Pico hydro system were examined as part of an ongoing development. Two configurations of the penstock having 2 and 1 stages of area reductions from 3 to 2 inches and 3 to 2 inches within the lower 1 m of their total height were used. Turbine runners with flat blades laterally twisted at angles of 30, 45, 60, 75 and 90° were fabricated locally and the system performance studied. The speed of rotation of the alternator and turbine shafts were measured and the available fluid power, flow rate and net head were computed. The results show that the 90° blade twist gave the best performance of the simplified system in terms of rotational speed and consequently power for both penstock configurations while the 30° twist yielded the least values of the parameters. However, the respective values for the 1st configuration were relatively higher for all the twist angles used. The maximum values of the parameters obtained for the 2-stage area reduction were 1844.7 rpm and 3636 W while the corresponding values for the other configuration were 1810.6 rpm and 2422 W The simplicity of the flat blade configuration coupled with the system performance for the entire blade twist angles indicates good promise for the implementation of the system for generation of clean, decentralized energy in line with current global trends even in locations without naturally flowing water.

Effect of integrated nutrient management on growth, yield and quality of broccoli (Brassica oleraceae var. italica L.) cv. Calabrese under foothill condition of Nagaland

A field experiment was carried out at the Experimental Farm, Department of Horticulture, School of Agricultural Sciences and Rural Development, Nagaland University, Medziphema Campus, during 2012-2013 and 2013-2014 to find out the response of integrated nutrient management on growth, yield and quality of broccoli cv. Calabrese under the foothill condition of Nagaland. Results revealed that integrated application of 50% NPK + 50% vermicompost + Biofertilizers recorded significantly higher plant height (70.33 cm), number of leaves (20.45), stem diameter (3.25 cm), plant spread (74.25 cm), equilateral head diameter (16.97 cm), polar head diameter(18.37 cm), head size (310.59 cm2), gross head weight (956.0 g), net head weight (330.86 g), yield ha-1 (11.96 t ha-1), protein content (3.77%), vitamin C content (132.50 mg 100 g-1), total soluble solids (5.52) and pH of the head (5.12). While treatment T16- 50% NPK + 50% Pig manure + Biofertilizers gave the highest net return (¹ 260450) and cost benefit ratio (1:3.48) and was found to be significantly at par for all growth, yield and quality parameters with treatment T18 (50% NPK + 50% vermicompost + biofertilizers).

An analysis of the impact of draft tube modifications on the performance of a Kaplan turbine by means of computational fluid dynamics

Due to the low electricity prices in central Europe, cost optimisations related to all parts of a new hydropower plant have become increasingly important. In case of a run-of-river hydropower plant using a vertical axis Kaplan turbine, one of the cost drivers are the excavation works. Thus, a decisive factor for the reduction of construction costs is the minimisation of the construction depth of the elbow-type draft tube. In course of the design phase of a new hydropower plant in Austria, an analysis of the impact of draft tube modifications on the performance of the Kaplan turbine was carried out by applying computational fluid dynamics. The net head of the turbine with a diameter of D = 3.15 m accounts for Hnet = 9.00 m and the maximum discharge per unit is Qmax = 57.5 m3/s. After it was proven that there is a good agreement of the numerically calculated and experimentally measured turbine efficiency for the original turbine configuration, various draft tube designs were tested in order to find out their impact on the turbine efficiency and to analyse the sources of draft tube losses in detail. Finally, it was possible to find a new draft tube design representing a compromise of reduced construction costs and acceptable turbine efficiency.

Performance prediction of a prototype tidal power turbine by using a suitable numerical model

For tidal power stations, turbines operate in a wide head range and sometimes near the free surface due to tide changes, which commonly consists of short intake channel. When they operate under low water levels, free surface flows would be a major concern for hydraulic stability. The present paper establishes a simulation method for predicting all flow fields in tidal power stations. Two-phase simulation model is introduced with the acceleration of gravity and the free surface, which consists of a turbine unit and two reservoir models (sea side and reservoir side). Hydraulic performance of a prototype turbine was predicted by using the proposed model, based on water levels of both two sides. The predicted unit performance agreed well with the test result. The flow fields were compared with ones by two other simulation methods. The proposed method could predict non-uniform intake flow inducing head losses by the sudden contraction and the gravity force, which sufficiently influenced turbine internal flows. Consequently, head drops in each part of the turbine were distributed differently, under the same net head. The present model provides a foundation for predicting prototype turbine performances under not only tide changes but also air-water interactions.

ASSESSMENT OF PUMP’S PERFORMANCE IN WATER SUPPLY SYSTEMS – DATA COLLECTED FROM MULTIPLE CASE STUDIES

This paper reports the evaluation of pump’s efficiencies and its optimization potential, in three water supply systems. The study surveyed 65 pumps groups, from 24 pumping stations, between 5 to 350 kW of absorbed power, with flow rates from 25 to 1500 m3/h. The performance of the pumps, was assessed by testing each pump group in different operational conditions. It was quantified, for each pump group, the specific consumption (kWh/m3) and cost (€/m3) as well as the difference between the optimum efficiency point, for the specific net head of each installation, and their actual operating point. The identified energy inefficiencies and proposed corrective measures for each pump group were compiled in order to improve their efficiency. Most problems identified are oversized groups, valve problems and inadequate operational working points. On average the surveyed pump’s efficiencies were 10 percentage points below their reference values. In order to reduce the gap several improvement measures were proposed, such as the refurbishment of the pumps, impeller adjustments, variable speed drive installation and the extension of the working periods with lower frequency regimes, where high efficiencies were identified. The implementation of these improvement measures has an energy saving potential of 331 MWh/year, which means 27.000 €/year.

Prediction of small hydropower plant power production in Himreen Lake dam (HLD) using artificial neural network

In developing countries, the power production is properly less than the request of power or load, and sustaining a system stability of power production is a trouble quietly. Sometimes, there is a necessary development to the correct quantity of load demand to retain a system of power production steadily. Thus, Small Hydropower Plant (SHP) includes a Kaplan turbine was verified to explore its applicability. This paper concentrates on applying on Artificial Neural Networks (ANNs) by approaching of Feed-Forward, Back-Propagation to make performance predictions of the hydropower plant at the Himreen lake dam-Diyala in terms of net turbine head, flow rate of water and power production that data gathered during a research over a 10year period. The model studies the uncertainties of inputs and output operation and there's a designing to network structure and then trained by means of the entire of 3570 experimental and observed data. Furthermore, ANN offers an analyzing and diagnosing instrument effectively to model performance of the nonlinear plant. The study suggests that the ANN may predict the performance of the plant with a correlation coefficient (R) between the variables of predicted and observed output that would be higher than 0.96.

Determination of turbine relative efficiency in SHPP

To assess the fulfillment of contract conditions for the equipment delivery, determining the properties and capabilities of a generating unit or some part of it, the measurements carried out under real operating conditions were necessary. In this paper, the results of the test that was carried out in a small hydropower plant (SHPP), aimed at determining the relative efficiency of the hydraulic turbine and its comparison with the guaranteed values, are presented. The dependence of the turbine efficiency on the turbine discharge was determined based on the test results, using the index method. The test was performed at one net head.

Simulation of the Francis-99 Hydro Turbine During Steady and Transient Operation

Numerical simulation of the Francis-99 hydroturbine with correlation to experimental measurements are presented. Steady operation of the hydroturbine is analyzed at three operating conditions: the best efficiency point (BEP), high load (HL), and part load (PL). It is shown that global quantities such as net head, discharge and efficiency are well predicted. Additionally, time-averaged velocity predictions compare well with PIV measurements obtained in the draft tube immediately downstream of the runner. Differences in vortex rope structure between operating points are discussed.Unsteady operation of the hydroturbine from BEP to HL and from BEP to PL are modeled. It is shown that simulation methods used to model the steady operation produce predictions that correlate well with experiment for transient operation.Time-domain unsteady simulation is used for both steady and unsteady operation. The full-fidelity geometry including all components is meshed using an unstructured polyhedral mesh with body-fitted prism layers. Guide vane rotation for transient operation is imposed using fully-conservative, computationally efficient mesh morphing. The commercial solver STAR-CCM+ is used for all portions of the analysis including meshing, solving and post-processing.

Estimation of the cost of electro-mechanical equipment for small hydropower plants – review and comparison of methods

The estimate of the cost of electro-mechanical equipment for new small hydropower plants most often amounts to about 30-40% of the total budget. In case of modernization of existing installations, this estimation represents the main cost. This matter constitutes a research problem for at least few decades. Many models have been developed for that purpose. The aim of our work was to collect and analyse formulas that allow estimation of the cost of investment in electro-mechanical equipment for small hydropower plants. Over a dozen functions were analysed. To achieve the aim of our work, these functions were converted into the form allowing their comparison. Then the costs were simulated with respect to plants’ powers and net heads; such approach is novel and allows deeper discussion of the problem, as well as drawing broader conclusions. The following conclusions can be drawn: significant differences in results obtained by using various formulas were observed; there is a need for a wide study based on national investments in small hydropower plants that would allow to develop equations based on local data; the obtained formulas would let to determinate the costs of modernization or a new construction of small hydropower plant more precisely; special attention should be payed to formulas considering turbine type.

Optimal Long-Term Hydro Generation Scheduling of Small Hydropower Plant (SHP) using Metaheuristic Algorithm in Himreen Lake Dam

This study focuses on the improvement of optimization model by applying particle swarm optimization and firefly algorithm methods to get a stable power production utility at its maximum level. Furthermore, it investigates on the minimization of utility loss in power production from the hydropower system, which is done by optimizing the variables of operation control in the hydropower plant at Lake Himreen - Diyala Dam. The variables mentioned are net turbine head, the rate of water flow and power production which had been gathered in the data during a research throughout a 10-year period. The results obtained from these two methods, namely Firefly Algorithm (FA) and Particle Swarm Optimization, (PSO) are compared. The inferences for general comparisons are created through several behavior indicators. The behavior indicators illustrate that FA's performance is better than PSO's performance, in some fields. At the end, the results show the strength of FA, as well as its efficiency and superiority.

Design, Modeling, and CFD Analysis of a Micro Hydro Pelton Turbine Runner: For the Case of Selected Site in Ethiopia

This paper addresses the design, modeling, and performance analysis of a Pelton turbine using CFD for one of the selected micro hydro potential sites in Ethiopia to meet the requirements of the energy demands. The site has a net head of 47.5 m and flow rate of 0.14 m3/s. The design process starts with the design of initial dimensions for the runner based on different literatures and directed towards the modeling of bucket using CATIA V5. The performance of the runner has been analyzed in ANSYS CFX (CFD) under given loading conditions of the turbine. Consequently, the present study has also the ambition to reduce the size of the runner to have a cost effective runner design. The case study described in this paper provides an example of how the size of turbine can affect the efficiency of the turbine. These were discussed in detail which helps in understanding of the underlying fluid dynamic design problem as an aid for improving the efficiency and lowering the manufacturing cost for future study. The result showed that the model is highly dependent on the size and this was verified and discussed properly using flow visualization of the computed flow field and published result.

CFD simulations of transient load change on a high head Francis turbine

Motivated by the importance of better understanding the structural integrity of high-head hydraulic turbines operating at intermittent conditions, complete 360º steady-state and transient simulations of a Francis turbine are presented in this paper. The main target of the work has been to investigate different numerical approaches such as mesh deformation for different operating conditions. Steady-state simulations were performed at the best efficiency point (BEP) and used as initial conditions for the transient simulations considering load rejection from BEP to part load (BEP2PL) and during load acceptance from BEP to high load (BEP2HL). Simulation results were compared with experimental data available for the Francis-99 project where close agreement was found for the mesh independent solution. The transient load analyses showed general trends in accordance with the measurement reports, especially for the pressure in vaneless space that is of high importance regarding RSI effects. Some deviations were identified for the net head at load rejection for which further investigations will be conducted. All CFD simulations were performed at model scale with ANSYS CFX v. 17 at either 96 or 120 cores (2.60 GHz). The immersed boundary technique was tested during the initial stages of the project, but had to be abandoned due to severe memory requirements. Pressure amplitudes and other instantaneous results were not considered.

Numerical simulation of cavitating flow in a centrifugal pump as turbine

In this study, the cavitating flow and cavitation performance are studied by employing the computational fluid dynamics method in the turbine mode of a centrifugal pump at part-load, best efficiency, and over-load points. The flow models are validated in the pump mode under noncavitation condition. The relationships between the performance variables and net positive suction head available are obtained, and the corresponding net positive suction heads required are extracted. The flow patterns, location, and shape of the cavity are illustrated; the pressure coefficient profiles on the blade surfaces are clarified and compared with those in the pump mode under both noncavitation and critical cavitation conditions. The cavitation performance and flow pattern as well as cavity shape in the turbine mode are distinguishably different from the pump mode. It is found out that the cavitation behavior in the turbine mode exhibits three notable features: a lower and less flow rate-dependent net positive suction head required, a flow rate-dependent suppressed rotational flow in the draft tube, as well as a rotational and extendable cavitating rope originated from the impeller cone. The results and methods can be important and useful for the design and selection of a centrifugal pump as turbine.

Influence of hydrophibization of impellers of centrifugal pumps on their operating characteristics

This work presents experimental estimation results of changing of basic operation characteristics of a group of centrifugal pumps covering a range of values of dimensionless power-speed coefficient ns from 33 to 330 after hydrophobization of their impellers' surfaces. Hydrophobization of functional surfaces of impellers in all experiments was performed by formation of structures of organic covers by technology of MPEI NRU, which provides increasing of limiting wetting angle of surfaces to 120° and greater. Results of experimental researches of the influence of hydrophobization of impeller surfaces for high-speed pump (ns = 330) on its characteristics is presented for the first time. Positive effect of applying hydrophobization technology to impeller surfaces in all the considered range of power-speed coefficient was generalized and estimated. It was shown that hydrophobization of impeller surfaces of centrifugal pumps provides increment to their efficiency factors within an acceptable operation range from 0.5 to 7.5%. Empiric function defining dependencies of efficiency factor increment of pump on relative supply and power-speed coefficient are suggested. Possibilities and estimation of extending acceptable operation range of a pump depending on powerspeed coefficient as a result of impeller surface hydrophobization are shown. Experimental data of comparative cavitation tests of high-speed pumps before and after hydrophobization of their impeller surfaces are generalized for the first time for considered range of power-speed coefficient values. The influence of power-speed coefficient on changing of critical net pump suction head (critical positive suction pressure) is shown. Based on existing knowledge on pumps, an attempt to validate experimentally obtained lows of changing of power and anticavitation features of centrifugal pumps after hydrophobization of their impeller surfaces is made.