A heat engine that propels a ship produces 500 Btu/lbm of work while rejecting 300 Btu/lbm of heat. What is its thermal efficiency?

A country needs to build new power plants to meet the increasing demand for electric power. One possibility is to build coal-fired power plants, which cost $1300 per kW to construct and have an efficiency of 40 percent. Another possibility is to build clean-burning Integrated Gasification Combined Cycle (IGCC) plants where the coal is subjected to heat and pressure to gasify it while removing sulfur and particulate matter from it. The gaseous coal is then burned in a gas turbine, and part of the waste heat from the exhaust gases is recovered to generate steam for the steam turbine. The construction of IGCC plants costs about$1500 per kW, but their efficiency is about 48 percent. The average heating value of the coal is about 28,000,000 kJ per ton (that is, 28,000,000 kJ of heat is released when 1 ton of coal is burned). If the IGCC plant is to recover its cost difference from fuel savings in five years, determine what the price of coal should be in $ per ton.

A food freezer is to produce a 5-kW cooling effect, and its COP is 1.3. How many kW of power will this refrigerator require for operation?

A completely reversible heat pump has a $\mathrm{COP}$ of $1.6$ and a sink temperature of $300 \mathrm{~K}$. Estimate (a) the temperature of the source and $(b)$ the rate of heat transfer to the sink when $1.5 \mathrm{~kW}$ of power is supplied to this heat pump.

A thermodynamicist claims to have developed a heat engine with 50 percent thermal efficiency when operating with thermal energy reservoirs at 1260 R and 510 R- Is this claim valid?

A heat engine that propels a ship produces 500 Btu / 1bm of work while rejecting 300 Btu / 1 bm of heat. What is its thermal efficiency?

A heat engine with a thermal efficiency of 45 percent rejects 500 kJ/kg of heat. How much heat does it receive? Answer: 909 kJ/kg

A steam power plant with a power output of 150 MW consumes coal at a rate of 60 tons/h. If the heating value of the coal is 30,000 kJ/kg, determine the overall efficiency of this plant.

A heat engine has a total heat input of 1.3 kJ and a thermal efficiency of 35 percent. How much work will it produce?

Find the 10th term of each of the following arithmetic sequences: 101, 97, 93, 89, ....

An ideal gas expands in an adiabatic turbine from 1200 K and 900 kPa to 800 K. Determine the turbine inlet volume flow rate of the gas, in $m^{3} / s$ required to produce turbine work output at the rate of 650 kW. The average values of the specific heats for this gas over the temperature range and the gas constant are $c_{p}=1.13 \mathrm{kJ} / \mathrm{kg} \cdot \mathrm{K}, c_{v}= 0.83 \mathrm{kJ} / \mathrm{kg} \cdot \mathrm{K}, \text { and } R=0.30 \mathrm{kJ} / \mathrm{kg} \cdot \mathrm{K}$

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A completely reversible heat pump has a COP of 1.6 and a sink temperature of 300 K. Calculate (a) the temperature of the source and (b) the rate of heat transfer to the sink when 1.5 kW of power is supplied to this heat pump.

A steam power plant receives heat from a furnace at a rate of 280 GJ/h. Heat losses to the surrounding air from the steam as it passes through the pipes and other components are estimated to be about 8 GJ/h. If the waste heat is transferred to the cooling water at a rate of 165 GJ/h, determine (a) net power output and (b) the thermal efficiency of this power plant. Answers: (a) 29.7 MW, (b) 38.2 percent