Question

в топке тепловой машины за 2 часа полностью сгорает 100кг торфа.найдите кпд этой тепловой машины,если ее механическая мощность равна 60кВт, а при сгорании 1кг торфа выделяется количество теплоты ,равное 24МДж. объясните решение пожалуйста!

Answer 1

Записываешь формулу КПД, полезная работа равна мощности, затраченная работа равна

количеству теплоты, выделившейся за два часа со 100 кг топлива.Находишь КПД. 

Answer 2

Calculating the Efficiency of a Heat Engine

To calculate the efficiency of the heat engine, we can use the formula for thermal efficiency:

Efficiency (η) = (Useful output energy / Input energy) × 100%

In this case, the useful output energy is the mechanical power produced by the engine, and the input energy is the heat energy obtained from the combustion of the peat.

Given Data

- Mass of peat burned (m) = 100 kg - Mechanical power (P) = 60 kW - Heat energy released per kg of peat (Q) = 24 MJ/kg

Solution

First, we need to calculate the total heat energy obtained from the combustion of 100 kg of peat.

Total heat energy (Q_total) = Mass of peat burned × Heat energy released per kg Q_total = 100 kg × 24 MJ/kg

Now, we can convert the total heat energy to kilowatts (kW) to match the unit of mechanical power.

1 MJ = 1,000,000 J 1 kW = 1,000 J/s

Q_total = (100 kg × 24,000,000 J) / (3,600,000 J/kWh) Q_total = 666.67 kWh

Now, we can calculate the efficiency using the formula mentioned earlier.

Efficiency (η) = (Useful output energy / Input energy) × 100% η = (P / Q_total) × 100% η = (60 kW / 666.67 kWh) × 100% η ≈ 9%

Explanation

The efficiency of the heat engine is approximately 9%. This means that 9% of the total heat energy obtained from the combustion of peat is converted into mechanical power, while the rest is lost as waste heat.

This calculation is based on the given mechanical power and the heat energy released per kg of peat. It's important to note that the actual efficiency may vary based on factors such as the specific design and operating conditions of the heat engine.

I hope this helps! If you have further questions or need additional assistance, feel free to ask.