Refrigerators and heat pumps — COP: Foundations — Hinglish deep dive

1.7.20 · D1 · Physics › Thermodynamics › Refrigerators and heat pumps — COP

Parent page par ek bhi formula padhne se pehle, aapko pictures padhni aani chahiye. Yeh page har ek symbol build karta hai jo topic use karta hai, ek ek karke, bilkul zero se. Yahan kuch bhi assumed nahi hai — agar main note ne kisi cheez ka sahara liya, toh hum use yahan construct karte hain.

1. Heat, aur yeh kis taraf flow karti hai

Sabse important ek fact — jis par poora chapter fight karne ke liye bana hai:

Figure — Refrigerators and heat pumps — COP

2. Reservoirs, aur do temperatures $T_{H}$ , $T_{C}$

Temperature ko apna careful build chahiye, kyunki parent topic quietly ek particular scale maangta hai.

Definition Kelvin — absolute temperature scale

Shabdon mein: Celsius (°C) apna zero paani ke freezing point par rakhta hai — yeh ek human convenience hai, physical zero nahi. Kelvin (K) apna zero absolute zero par rakhta hai, jahan kuch bhi ho sakta hai sabse thanda, jahan saari thermal motion ruk jaati hai. Convert karein: $T (K) = T (° C) + 273$ . Picture: ek thermometer jiska neechi waala end "bilkul koi heat nahi bachi" par thaka hua hai, na ki "ice pighalta hai" par. Topic ko iske zaroorat kyun hai: Carnot formulas mein $T_{C} / (T_{H} - T_{C})$ jaise ratios hote hain. Ek ratio tabhi physical sense banata hai jab $0$ ka matlab "truly nothing" ho. Celsius scale par $0$ arbitrary hai, isliye Celsius temperatures ka ratio meaningless hai. Yeh parent page par #1 galti hai — hamesha pehle kelvin mein convert karo.

3. Work $W$ — woh price jo aap pay karte ho

Yahan poori machine ek energy diagram ke roop mein hai — teen arrows yaad karo.

4. Ek "cycle" aur energy balance kyun hota hai

5. Ratios, aur "COP" ko benefit ÷ cost ke roop mein padhna

6. Entropy $S$ aur $Q / T$ bookkeeping

Carnot (best-possible) formulas ko ek aur idea chahiye, Entropy aur Second Law of Thermodynamics se liya hua.

Definition Entropy transfer

$Q / T$ — "heat ke saath kitna disorder travel karta hai" Shabdon mein: jab heat $Q$ temperature $T$ (kelvin mein) par cross karti hai, toh yeh $Q / T$ ke barabar entropy carry karti hai. Entropy "spread-out-ness" ya disorder ka measure hai. Picture: wahi heat ek cold body ko dene par "zyada disorder worth" hoti hai (chhota $T$ , bada $Q / T$ ) ek hot body ko dene se zyada (bada $T$ , chhota $Q / T$ ). Topic ko iske zaroorat kyun hai: ek perfect (reversible, Carnot) machine koi extra entropy generate nahi karta, isliye cold se kheenchi gayi entropy hot par dump ki gayi entropy ke barabar hoti hai: $\frac{Q _{C}}{T _{C}} = \frac{Q _{H}}{T _{H}} \Rightarrow \frac{Q _{H}}{Q _{C}} = \frac{T _{H}}{T _{C}} .$ Yeh akeli condition hi messy heat ratio ko ek clean temperature ratio mein badal deti hai, jo Carnot COPs $\frac{T _{C}}{T _{H} - T _{C}}$ aur $\frac{T _{H}}{T _{H} - T _{C}}$ deti hai.

Foundations topic ko kaise feed karte hain

Ise top-down padho: heat, work aur cycle energy balance dete hain; balance aur ratio idea milkar COP dete hain; kelvin temperatures aur entropy add karne par Carnot limit milti hai.

Equipment checklist

Khud ko test karo — aap parent note ke liye tabhi ready ho jab har reveal wohi ho jo aap kehte.

Heat

Q

kya hai aur uski unit kya hai?

Energy jo bodies ke beech cross karti hai temperature difference ki wajah se; joules (J) mein measure hoti hai.

Heat apne aap kis taraf flow karti hai?

Neeche ki taraf — sirf hot se cold. Ise ulta karne ke liye work chahiye.

Reservoir kya hota hai?

Itna bada body ki heat add ya remove karne par uska temperature fixed rehta hai.

T_{H}

aur

T_{C}

kya label karte hain?

Hot reservoir temperature (jahan dump kiya jaata hai) aur cold reservoir temperature (jahan se kheencha jaata hai), jahan

T_{H} > T_{C}

Temperatures kelvin mein kyun honi chahiye, Celsius mein kyun nahi?

Carnot formulas temperature ratios use karte hain, jo tabhi sense banate hain jab 0 absolute zero ho (sach mein "koi heat nahi"), na ki arbitrary Celsius zero.

27 °C ko kelvin mein convert karo

27 + 273 = 300

Yahan work

W

kya hai, aur iska kya role hai?

Energy jo mechanically/electrically push ki jaati hai (compressor); yeh cost hai jo aap pay karte ho, COP ka denominator.

Energy balance batao aur yeh kyun hold karta hai

Q_{H} = Q_{C} + W

, kyunki ek cycle mein

Δ U = 0

isliye energy in energy out ke barabar hoti hai.

Cycle mein

Δ U = 0

kyun hota hai?

Working substance apni exact starting state par wapas aata hai, isliye uski internal energy unchanged rehti hai.

COP usually 1 se bada kyun hota hai?

Yeh heat moved per work paid hai (ek leverage ratio), energy convert ki gayi ka fraction nahi — aap jo work spend karte ho usse zyada heat move kar sakte ho.

Reversible (Carnot) case ko define karne wali entropy condition kya hai?

Q_{C} / T_{C} = Q_{H} / T_{H}

, yaani koi net entropy create nahi hoti, jisse

Q_{H} / Q_{C} = T_{H} / T_{C}

milta hai.

Connections

Parent: Refrigerators and heat pumps — COP — woh topic jise yeh foundations unlock karte hain.
First Law of Thermodynamics — $Δ U_{cy c l e} = 0$ ke zariye $Q_{H} = Q_{C} + W$ balance ka source.
Entropy — reversible heat ratio ke peeche $Q / T$ bookkeeping.
Second Law of Thermodynamics — free uphill heat flow ko forbid karta hai, aapko $W$ pay karne par majboor karta hai.
Carnot Cycle — reversible machine jo maximum COP set karti hai.
Heat Engines and Efficiency — wohi teen quantities $Q_{H}, Q_{C}, W$ ulti direction mein chalti hain.