PhysicsHiranyagarbha · Class 11-12
Hydropower ka model: P = ηρgQH aur uske trade-off
Run-of-the-river project ko 'kam asar wala' kaha jaata hai — phir 237 metre ooncha storage dam usi naam mein kaise fit hota hai?
Socho pehle… phir dekho jawab
Physics mein power ke do lever hain: head (H) aur discharge (Q). Run-of-the-river mostly flow par chalta hai, kam storage ke saath. Oonchi deewar head aur storage dono badhati hai — aur baadh-niyantran ke liye storage hi chahiye. Card khud is contradiction ko pakadta hai.
Model: P = η ρ g Q H. ρ = paani ka density (~1000 kg/m³), g = 9.8 m/s², Q = discharge (m³/s), H = net head (m), η = overall efficiency (turbine × generator). Derivation: har second Q m³ paani, yaani ρQ kg, H neeche girta hai → potential energy ka rate ρQgH. Net head gross head se kam hota hai, kyunki pipe (penstock) mein friction se head loss hota hai.
Energy chain: potential → kinetic (penstock mein) → turbine ka rotation → generator mein electromagnetic induction (coil aur magnetic field ki relative gati se EMF) → grid. Tez dhalaan aur zyada discharge wali Himalayan nadiyaan dono lever ek saath deti hain.
Trade-off: run-of-the-river — kam storage, isliye sookhe mausam mein kam bijli, par neeche ki nadi ka flow kam badalta hai. Storage — firm aur flexible power (solar-wind ko balance), baadh-niyantran; par neeche ka flow, sediment aur jal-jeevon ka safar badalta hai, aur dam-safety aur GLOF (glacial lake ke achanak phootne se baadh) jaise risks ka hisaab zaroori hai.
Ghar pe try karo
Example numbers se calculation karo: Q = 200 m³/s, H = 150 m, η = 0.9. P kitne MW? Ab H aadha karo — P? Ab Q aadha karo — P? Phir ek line mein likho: linear relation engineers ko H aur Q ke beech kaunsa trade-off chunne deta hai.
Wow!
Card khud poochta hai ki jo project 'run-of-the-river' kehlata hai, uske paas 237 m ooncha storage dam kaise — physics ki bhasha mein, baadh-niyantran bina bade reservoir ke aata hi nahi.
3 sawaal
- P = ηρgQH mein Q kya hai?
Jawab dekho
Discharge — har second bahne wale paani ka volume. Q discharge hai, m³/s mein.
- Net head gross head se kam kyun hota hai?
Jawab dekho
Penstock mein friction se head loss. Pipe ki friction kuch energy kha jaati hai, jise head loss kehte hain.
- Generator bijli kis principle par banata hai?
Jawab dekho
Electromagnetic induction. Coil aur magnetic field ki relative gati se EMF paida hota hai.
NCERT se jodo: NCERT Class 11 Physics — work, energy and power; Class 12 Physics — electromagnetic induction