What is the difference between air standard assumptions and the cold air standard assumptions?
♨Along with all the above assumptions, taking constant specific heats at room temperature, at 25 C for air, is called cold air standard assumptions. ✔Assuming constant specific heats at room temperature 25 C for air is only the difference between air standard assumptions and cold-air standard assumptions.
What are air standard cycles?
The air-standard cycle is an idealized cycle founded on the following approximations: (1) The working fluid throughout the cycle is only air; (2) the air acts as an ideal gas; (3) combustion processes are replaced by well-defined heat addition processes; and (4) the exhaust process is replaced by a heat rejection …
What is the meaning of Otto cycle?
heat, and removal of heat
What is dual cycle in thermodynamics?
Dual cycle, or limited pressure cycle, is a thermodynamic cycle that combines the Otto cycle and the Diesel cycle. In the dual cycle, combustion occurs partly at constant volume and partly at constant pressure. It can be used to describe internal combustion engines.
Why is the dual cycle known as a mixed cycle?
In this cycle, part of heat addition occurs at constant volume while the rest is at constant pressure. The dual cycle is also called mixed or limited pressure cycle. This thermal efficiency can be converted in terms of measurable quantities as it was done for Otto and Diesel cycle.
How do you calculate the cut off ratio of a diesel cycle?
The cutoff ratio is the ratio of the volume after combustion to the volume before combustion. From the above equation, it is observed that, the thermal efficiency of the diesel engine can be increased by increasing the compression ratio, Ro, by decreasing the cut-off ratio, rc, or by using a gas with large value of γ.
What is the reciprocal of cutoff ratio?
Mechanical Engineering :: Steam Boilers and Engines The cut-off ratio is the reciprocal of expansion ratio, A. 32.
What is cut-off ratio in dual cycle?
9-54 An ideal dual cycle has a compression ratio of 14 and cutoff ratio of 1.2. The thermal efficiency, amount of heat added, and the maximum gas pressure and temperature are to be determined. 3 Air is an ideal gas with constant specific heats.
How is the compression ratio of a piston engine determined?
The compression ratio is defined as the ratio between the volume of the cylinder with the piston in the bottom position, Vbottom (largest volume), and in the top position, Vtop (smallest volume). The higher this ratio, the greater will be the power output from a given engine. It is generally in the 6–10 range.
Does higher compression mean more power?
This occurs because internal combustion engines are heat engines, and higher compression ratios permit the same combustion temperature to be reached with less fuel, while giving a longer expansion cycle, creating more mechanical power output and lowering the exhaust temperature.