Question

Який ККД бензинового пальника ("примусу"), якщо при спалю-ванні 73 г бензину він нагріває 5 л води на 40 0С ? Питома теплота зго-ряння бензину 4,6·107 Дж/кг.

Answer 1

ККД = Q_(корисне)\Q_(повне) * 100%

Q_(корисне)=c*m*Dt 

Q _(повне)=q*m

Q_(повне)= 44000кДж\кг * 0,073кг= 3212кДж= 3212000Дж= 3,212 МДж 

m_(води)= густинва води * обэм води= 1000кг\м^3 * 5л = 5000кг 

Q _(корисне)= 4200Дж\кг*0С * 5000кг * 40 0С = 840000000Дж= 840МДж

ККД= 840МДж\3,212МДж * 100% = 26151,93% 

Answer 2

Calculating the Efficiency of the Primus Stove

To calculate the efficiency of the primus stove, we can use the formula for efficiency:

Efficiency = (Energy output / Energy input) * 100%

In this case, the energy input is the heat energy produced by burning 73 g of gasoline, and the energy output is the heat energy required to heat 5 L of water from 20°C to 40°C.

Calculating Energy Input

The energy input can be calculated using the formula:

Energy input = mass of fuel × specific heat of fuel × calorific value of fuel

Given: - Mass of fuel (m) = 73 g - Specific heat of fuel = not provided - Calorific value of fuel (Q) = 4.6 × 10^7 J/kg

We can calculate the energy input using the provided calorific value of gasoline.

Calculating Energy Output

The energy output can be calculated using the formula:

Energy output = mass of water × specific heat of water × temperature change

Given: - Mass of water (m) = 5 L - Specific heat of water (c) = 4.18 J/g°C - Temperature change (ΔT) = 40°C - 20°C = 20°C

We can calculate the energy output using the mass of water, specific heat of water, and the temperature change.

Calculations

Let's calculate the efficiency of the primus stove using the provided information and the formulas mentioned above.