What is the maximum performance of crossflow turbine?

By Amad Suhendra

Sonnek (1923) modified the banki theory assuming a constant angle of the blade equal to 30 , so that the expression resulted in maximum performance:

ηmax = 0.863-0.264 *(D / H)

D is the diameter of turbine (disc) and H is the net head

Ref : Ariel R.Marchegiani , "Turbina de Flujo Transversal O Michell-Banki", Universidad Nacional Del Comahue

The Future of Microalgae in Clean Technologies

By Jean VanderGheynst (jsvander@ucdavis.edu)

"There is no magic- bullet fuel crop than can solve our energy woes without harming the environment, says virtual every scientist studying the issue. But most say that algae....comes closer than any other plant"

Green Dreams- National Geographic, october 2007

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IMIDAP - Guide books for MHP feasibility study in Indonesia

IMIDAP
(Integrated Micro-Hydro Development and Application Program)

The overall objectives of IMIDAP are:

1. To enhance interest among the Indonesian private sector in the micro-hydro power business;
2. To increase the number of community-based micro-hydro projects as a result of effective institutional capacity building;
3. To improve the availability, and local knowledge, of micro-hydro technology applications in the potential locations of micro-hydro development;
4. To increase private sector and rural community joint implemen-tation of micro-hydro projects.
   

DOWNLOADS FS Guide books for MHP

1. Pedoman UMUM Penyusunan Studi Kelayakan PLTMH [BUKU UTAMA]*

2. Pedoman Studi Potensi (Pra Studi Kelayakan) [BUKU 1]*

3. Pedoman Teknis Standarisasi Peralatan dan Komponen PLTMH*

4. Pedoman Studi Kelayakan Hidrologi [BUKU 2 A]*

5. Pedoman Studi Kelayakan Sipil [BUKU 2 B]*

6. Pedoman Studi Kelayakan Mekanikal Elektrikal [BUKU 2 C]*

7. Pedoman Studi Kelayakan Ekonomi / Finansial [BUKU 2 D]*

8. Pedoman Studi Kelayakan Sosial Budaya [BUKU 2 E]*

9. Pedoman Studi Kelayakan Lingkungan [BUKU 2 F]*

10. Pedoman Studi Komprehensif Berkelanjutan [BUKU 2 G]*

11. Pedoman Penyusunan Laporan Studi Kelayakan Teknis [BUKU 3]*

How to calculate the diameter and number of nozzles for Pelton turbine

By Ahmad Suhendra

Example :

A Pelton turbine is planned to be working on the head netto 80 m and a flow 20 liters / s , what is the number of nozzles installed on these turbines?

Pelton turbine requirements are :

• ns (specific speed , rpm) = 8 – 72 rpm
• Nominal speed = 500 – 1500 rpm

1.Specific speed of turbine

• Taken 1500 rpm as nominal turbine speed (N_turbine)
• Flow (Q) = 0.020 m3/s
• H_netto = 80 m

ns = 3.65 *N_turbine (rpm) * Q(m^3/s) 0.5 / H_netto(m)^ 0.75

= 3.65 * 1500 rpm * (0.020 m3/s)^0.5 / (80 m)^0.75

= 774.28 / 26.75 = 28.95 rpm

Based on the practical calculation,

• If ns >= (8) and < (29.5) then 1 nozzles
• If ns >= (29.5) and < (42) then 2 nozzles
• If ns >= (42) and < (54) then 3 nozzles
• If ns >= (54) and < (58) then 4 nozzles
• If ns >= (58) and <=(72) then 6 nozzles

ns = 28.95 rpm -------> Ok, Pelton turbine with one nozzles

2. Absolute velocity of water

kc ( nozzles coef.) = 0.96 to 0.98, Taken kc = 0.98

C = kc (2 * 9.8 m/s^2 * H_netto(m) )^ 0.5

= 0.98 (2 x 9.8 x 80 ) 0.5 = 38.81 m/s

3. Diameter of nozzles

Dn = [ (4 x Q/(number of nozzles)) / (phi x C) ] ^0.5

= [ 4 x (0.020/1) / (3.14 x 38.81)] ^0.5

= [ 0.08 / 121.86 ] 0.5 = 0.0256 m or 26 mm

Ref : Edy Sunarto dan Markus Einsering”,Turbin Pelton Mikro”, MHPG Andi Offset Yogyakarta 1992

Calculation of penstock diameter

By Ahmad Suhendra

Penstock serves to drain the water into the turbine, because water power is a combination of head (H) and flow (Q). Water will flow down and create pressure on the end of the pipe that provides power to rotate the turbine,

Example

• Penstock length (Lp) = 15 m
• Flow (Qp) = 2.0 m³/sec
• H gross = 9 m
• Manning Coef (n) = 0.012 (value of the Manning roughness coefficient for Mild steel )

What is the diameter and head loss of the penstock ?
1. Penstock diameter (Dp)

• Dp = [C Qp / V ]^0.5 
• C (constants) = 1.273 = 4 / (phi)
• V (water velocity ) = 1 - 2.8 m / sec.
• Taken, V = 1.6 m / sec.)*
• Dp = [1.273 (2.0 / 1.6)] ^0.5 = 1.261 m ( penstock diameter)

2. Head loss

Assumed there are only head loss due to friction in penstock (applying the manning formulae), then :

• Head loss = [(10.29 n ² Q_p² )/ D_p^5.333] L_p 
• = 0.114 m
• Percent of Head loss = (0.114 m / 9 m ) * 100 % = 1.27 %)*

Note )* :

• Generally, for economic reasons the percent of head loss between 5 % to 10 %
• [Permissible velocity in Penstocks,V(m/s) = 0.125 (2 g H)^0.5, Ref : USBR (1961) (P J Bier)]
• If using Sarkaria's eq ==>; Dp = 3.55 ((Qp^2/(2 g H ))^0.25 = 1.377 m

Ref : ESHA (European Small Hydropower Association),”Layman’s Handbook on How To Develop a Small Hydro Site,”2nd ed, 1998

Examples of open-channel calculation

1. What are the types of open channel flow?
2. Water is flowing at a velocity of 12 ft/s and depth of 10 ft in a channel of rectangular section. Find the change in depth and absolute water level produced by (a) the smooth upward step of 0.5 ft, (b) the smooth downward step of 1 ft in the channel bed. Also (c) find the maximum allowable size of upward step for the upstream to be possible as specified.
3. etc

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Electric Generator Selection for micro hydro system

The first problem that arises from this power plant is the determination of the generator to be used, generator simultaneously (synchronous generator) or no-simultaneous generator (asynchronous generator), both for the rotor cage and the rotor turns. The generator with permanent magnet is also being developed as a solution to power generation turbines at low rotation without having to use the gear box.

The use of synchronous generator at the same time we make it easy to adjust the output voltage and frequency generator by regulating the field current of the generator. Unfortunately, the use of synchronous generator at the same time rarely applied due to the expensive cost, requires current amplifier and requires complex control systems.

Asynchronous generator is often used for wind turbine systems and micro hydro systems, both for fixed-speed systems and variable speed systems.

The advantage of fixed-speed system using asynchronous generators are cheap, simple and robust system. This system operates at a constant speed, so that the turbine only obtain at maximum power . This system is suitable for application in micro hydro that water flow rate can be regulated mechanically. The weakness of this system is the generator requires reactive power to generate electricity so that the capacitor banks should be installed. The system is vulnerable to the pulsating power and are prone to mechanical changes.

What is a Micro or Mini hydro

Micro hydro is a term used for the installation of power using the energy of water, while micro means small and hydro means water. Micro hydro energy, also known as white resources and classified in the zero emission energy for electricity, while those in the fossil fuel CO2 emission factors have as much as 0.719 kg / kWh. Terms of emphasis to more sustainable activities that are not harmful, harmonious with nature and the rule-abiding principle naturally, when the activities associated with the term Micro Hydro development is the effort to produce energy in harmony with the rule-principle of nature .As the real action is to maintain the ability of nature to provide energy to the water at any time to protect and maintain watershed or catchment area around the generator, so that the plants are expected to operate throughout the period.

Besides the term of Micro-Hydro above, we also often hear the term of Mini Hydro that distinguishes them is Micro hydro with a range of resources raised. According to the National Standards Indonesia (BSNI), Micro hydro power is raised from a maximum of 50 kW and Mini-hydro above 50 kW to 5000 kW. In the group of M.H.P(Micro Hydro Power) and academics rarely have they segregated the restrictions, to a maximum of 100 kW for Micro-hydro and above 100 kW to 500 kW for Mini-hydro.