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Adiabatical expansion: The gaseous detonation products return to a final pressure equal to the initial pressure, Ρ 0. Heat extraction: The gaseous products are reversibly cooled at a constant pressure to reach the initial temperature Τ 0. The cycle is completed by converting the products into reactants, as in the initial conditions.
Adiabatic expansion occurs when the pressure on an adiabatically isolated system is decreased, allowing it to expand in size, thus causing it to do work on its surroundings. When the pressure applied on a parcel of gas is reduced, the gas in the parcel is allowed to expand; as the volume increases, the temperature falls as its internal energy ...
As shown before, throttling keeps h constant. E.g. throttling from 200 bar and 300 K (point a in fig. 2) follows the isenthalpic (line of constant specific enthalpy) of 430 kJ/kg. At 1 bar it results in point b which has a temperature of 270 K. So throttling from 200 bar to 1 bar gives a cooling from room temperature to below the freezing point ...
Any thermodynamic processes may be used. However, when idealized cycles are modeled, often processes where one state variable is kept constant, such as: adiabatic (constant heat) isothermal (constant temperature) isobaric (constant pressure) isochoric (constant volume) isentropic (constant entropy) isenthalpic (constant enthalpy)
We assume the expansion occurs without exchange of heat (adiabatic expansion). Doing this work, air inside the cylinder will cool to below the target temperature. To return to the target temperature (still with a free piston), the air must be heated, but is no longer under constant volume, since the piston is free to move as the gas is reheated.
The dependence of work on the path of the thermodynamic process is also unrelated to reversibility, since expansion work, which can be visualized on a pressure–volume diagram as the area beneath the equilibrium curve, is different for different reversible expansion processes (e.g. adiabatic, then isothermal; vs. isothermal, then adiabatic ...
The efficiency η of a thermogravitational cycle depends on the thermodynamic processes the working fluid goes through during each step of the cycle. Below some examples: If the heat exchanges at the bottom and top of the column with a hot source and cold source respectively, occur at constant pressure and temperature, the efficiency would be equal to the efficiency of a Carnot cycle: [1]
The Rüchardt experiment, [1] [2] [3] invented by Eduard Rüchardt, is a famous experiment in thermodynamics, which determines the ratio of the molar heat capacities of a gas, i.e. the ratio of (heat capacity at constant pressure) and (heat capacity at constant volume) and is denoted by (gamma, for ideal gas) or (kappa, isentropic exponent, for real gas).