Chapter 1, Problem 1.61P

This question related to thermodynamics

In adiabatic process, the system has Q=max. value O W=0 O Q=0 O U-0 O * A vertical piston-cylinder device contains water and is being heated on top of a range. During the process, 65 Btu of heat is transferred to the water, and heat losses from the side walls amount to 8 Btu. The piston rises as a result of evaporation, and 5 Btu of work is done by the vapor. Determine the change in the energy of the water .for this process 61 Btu O 52 Btu 55 Btu 60 Btu * hp compressor in a facility that operates at full load-75 for 2500 h a year is powered by an electric motor that has an efficiency of 93 percent. If the unit cost of electricity is $0.11/kWh, the annual electricity cost of this :compressor is 16,540 $ 19,180 $ O 5,380 $ O 14,300 $ O barometric pressure or 1 atmospheric 1 pressure is equal to 1.019 kgf/cm2 1 kgf/cm2 0.9 kgf/cm2 0 kgf/cm2 O

Energy transfer in mechanical systems During steady-state operation, a mechanical gearbox receives 70 KW of input power through the input shaft and delivers power through the output shaft. Considering the gearbox as a thermodynamic system, the rate of convection heat transfer generated during its operation is defined by: Q = −hА(T₂ — Tƒ) where h=0.171 kW/m²-K is the convection heat transfer coefficient, A = 1.0 m² is the outer surface area of the gearbox, Tb = 300 K is the temperature of the outer surface, and Tƒ= 293 K is the temperature of the surrounding air. For the gearbox, evaluate the heat transfer rate, Q, and the power delivered through the output shaft, W.

If H is the work output of a heat engine and Q is the total heat input of an engine, then determine its thermal efficiency.

Based on the concept of heat transfer, explain the followings: i. How can the mountain be much colder than the sea level? ii. How does our sweat control the body temperature? iii. Why is most ofaircraft is painted in white? iv. How the microwave can heat the meal? V. How does the global warming happen?

In a closed rigid (unchangeable, rigid) tank, 0.5 kg of air is present at a temperature of 300 K. There is a heat transfer of 54 kJ from the environment to the tank. The final temperature of the air in the tank is calculated in k.

Q1: An aluminum pan whose thermal conductivity is 237 W/m-°C has a flat bottom whose diameter is 20 cm and thickness 0.6 cm. Heat is transferred steadily to boiling water in the pan through its bottom at a rate of 700 W. If the inner surface of the bottom of the pan is 105°C, determine the temperature of the outer surface of the bottom of the pan.

A firearm can be modeled as a kind of heat engine, where the projectile acts as a piston that separates from the rest of the system during expansion. Consider a rifle with a 1.70 kg barrel made of iron [specific heat = 448 J/(kg °C)]. The rifle fires a 4.00 g bullet that exits the barrel with a speed of 350 m/s. When the propellant is ignited, 1.10% of the energy released goes into propelling the bullet (this is the thermal efficiency of the "engine"). The other 98.9% can be approximated as being entirely absorbed by the barrel, which increases in temperature uniformly for a short time before this energy is dissipated into the surroundings. What is this temperature increase (in °C)? (Round your answer to at least one decimal place.) °℃

Heat transfer principles of convection