A well-established way of power generation involves the utilization of geothermal energy—the energy of hot water that exists naturally underground—as the heat source. If a supply of hot water at 140°C is discovered at a location where the environmental temperature is 20°C, determine the maximum thermal efficiency a geothermal power plant built at that location can have.

When you skid to a stop on your bike, you can significantly heat the small patch of tire that rubs against the road surface. Suppose a person skids to a stop by hitting the brake on his back tire, which supports half the 80 kg combined mass of the bike and rider, leaving a skid mark that is 40 cm long. Assume a coefficient of kinetic friction of 0.80. How much thermal energy is deposited in the tire and the road surface?

A heat engine operates between a reservoir at 28°C and one at 323°C. What is the maximum efficiency possible for this engine?

In 1903, Aegidius Elling of Norway designed and built an 11-hp gas turbine that used steam injection between the combustion chamber and the turbine to cool the combustion gases to a safe temperature for the materials available at the time. Currently there are several gas-turbine power plants that use steam injection to augment power and improve thermal efficiency. For example, the thermal efficiency of the General Electric LM5000 gas turbine is reported to increase from 35.8 percent in simple-cycle operation to 43 percent when steam injection is used. Explain why steam injection increases the power output and the efficiency of gas turbines. Also, explain how you would obtain the steam.

Suppose a heat engine is connected to two energy reservoirs, one a pool of molten aluminum (660°C) and the other a block of solid mercury (-38.9°C). The engine runs by freezing 1.40 g of aluminum and melting 16.0 g of mercury during each cycle. The heat of fusion of aluminum is 3.97 x 105 J/kg; the heat of fusion of mercury is 1.18 x 104 J/kg. What is the efficiency of this engine? 74.9 4 X Note that the usable energy in a heat engine is the difference between the energy input and the exhaust energy. % Need Help? Watch It Additional Materials eBook

A 100-kg steel support rod in a building has a length of 2.0 m at a temperature of 20°C. The rod supports a hanging load of 6 000 kg. Find (a) the work done on the rod as the temperature increases to 40°C, (b) the energy Q added to the rod (assume the specific heat of steel is the same as that for iron), and (c) the change in internal energy of the rod.

A one-dimensional chain consists of a set of N rods each of length a. When stretched by a load, each rod can align either parallel or perpendicular to the length of the chain. The energy of a rod is -ɛ when perpendicular to it. When the chain is in thermal equilibrium at temperature T, its average length is

Consider a heat engine transferring energy from a warm region (Tw) to a cool region (Tc) . Which combination of temperatures will result in the highest efficiency?

PROBLEM 4 A heat pump is used to meet the heating requirements of a house and maintain it at a comfortable temperature. On an average winter day, the house is estimated to lose heat at a rate of 80,000 kJ h¯¹. The heat pump has a COP of 2.5 under these conditions. Questions: (a) Determine the net power input required by the heat pump, in kW. (b) The rate at which heat is extracted from the cold outdoor air, in kW.

The first law of thermodynamics relates the heat transfer into or out of a system to the change of internal and the work done on the system.  How much heat, in joules, is transferred into a system when its internal energy decreases by 165 J while it was performing 27.5 J of work?