1. Calculate the theoretical maximum specific energy, that is the maximum available electrical energy per unit mass, of

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1. Calculate the theoretical maximum specific energy, that is
the maximum available electrical energy per unit mass, of an
idealized lithium-sulfur battery. Express your result in MJ/kg.
Take the battery voltage as 1.9 V and neglect the mass of
electrolyte. The half reactions are: Anode: Li  Li+ + eCathode: S
+ 2Li+ + 2e-  Li2S Take the masses as 6.94 g/mol for Li and 32.06
g/mol for S. Take the Faraday constant as 96485 C/mol. 2. Consider
an aircraft flying at constant velocity and altitude. It has mass,
m=175,000 kg, and a lift to drag ratio of 20. What thrust is
required to maintain level constant velocity flight? For this take
the gravitational force as mg with g=9.8 m/s2 . If the aircraft has
a velocity relative to the air of 250 m/s, what is the minimum
power that must be produced by the engines? If the engines produce
an output velocity of 375 m/s (relative to the engine), what is the
mass flow rate (mass of air per unit time) that is needed? What is
the power that engines must produce in this case? 3. Consider two
ideal engines using air (specific heat ratio, γ = 1.4). Engine A is
a compression ignition Otto cycle engine and engine B is a turbine
Brayton cycle engine. If both engines have a compression ratio, r =
20, what is the ratio of the efficiency of engine A to that of
engine B? 4. Consider a combined cycle power plant based on a
Brayton cycle gas turbine with exhaust used in a Rankine steam
cycle. The Brayton cycle has an efficiency of 22% and the Rankine
cycle has an efficiency of 36% in this plant. What is the
efficiency of the combined cycle? If the hot temperature in the
Brayton cycle is 1150 °C and the cold side of the Rankine cycle is
100 °C, what is the corresponding ideal Carnot cycle efficiency?
What is the ratio of the combined cycle efficiency to the Carnot
efficiency?