Question

Ри нагревании подсолнечного масла массой 754 г от 11°С до 57°С сожгли 4,2 г керосина. Определи КПД (коэффициент полезного действия) использованной нагревательной установки. Удельная теплоёмкость подсолнечного масла равна 1700 Дж/(кг·°С), удельная теплота сгорания керосина — 43 МДж/кг. Ответ (округли до десятых):

Answer 1

Ответ:

КПД=32.6 %

Объяснение:

m м=754 г=0.754 kг

ΔT=57-11=46° С

m k=4,2 г=0.0042 kг

c м=1700 Дж/(кг·°С)

λ=43 МДж/кг=43*10⁶Дж/кг

КПД ?

Q нагр=c м*m м*ΔT=1700*0.754*46=58963 Дж

Q сг=λ*m k=43*10⁶*0.0042=180600 Дж

КПД=Q нагр/Q сг=58963/180600*100=32.6 %

Answer 2

Calculation of Efficiency (КПД) of the Heating System

To calculate the efficiency (КПД) of the heating system, we need to determine the amount of heat absorbed by the sunflower oil and the amount of heat released by the burning of kerosene.

Given: - Mass of sunflower oil (m) = 754 g = 0.754 kg - Initial temperature of sunflower oil (T1) = 11°C - Final temperature of sunflower oil (T2) = 57°C - Mass of kerosene burned (m_kerosene) = 4.2 g = 0.0042 kg - Specific heat capacity of sunflower oil (c_oil) = 1700 J/(kg·°C) - Specific heat of combustion of kerosene (Q_kerosene) = 43 MJ/kg = 43,000,000 J/kg

To calculate the heat absorbed by the sunflower oil, we can use the formula:

Q_absorbed = m * c_oil * (T2 - T1)

Substituting the given values:

Q_absorbed = 0.754 kg * 1700 J/(kg·°C) * (57°C - 11°C)

Calculating the above expression:

Q_absorbed = 0.754 kg * 1700 J/(kg·°C) * 46°C = 58,982 J

To calculate the heat released by the burning of kerosene, we can use the formula:

Q_released = m_kerosene * Q_kerosene

Substituting the given values:

Q_released = 0.0042 kg * 43,000,000 J/kg = 180,600 J

The efficiency (КПД) of the heating system can be calculated using the formula:

Efficiency (КПД) = (Q_absorbed / Q_released) * 100

Substituting the calculated values:

Efficiency (КПД) = (58,982 J / 180,600 J) * 100 ≈ 32.6%

Therefore, the efficiency (КПД) of the heating system is approximately 32.6%.

Please note that the answer has been rounded to the nearest tenth as requested.