Throughout a throttling process___________________?
Show answer Hide answer
Answer: D. all of the above
Explanation
Throttling is a constant enthalpy process where fluid expands through a restricted valve or porous plug. No external work is extracted during this rapid pressure drop, keeping work done equal to zero. Insulated throttling valves experience negligible heat transfer, satisfying all conditions listed simultaneously. Joule-Thomson effect describes the temperature change of a gas or liquid during a throttling process. Entropy increases during throttling because the process is highly irreversible due to fluid turbulence. Enthalpy upstream equals enthalpy downstream despite the significant drop in static pressure.
Refrigeration systems use expansion valves to throttle high-pressure liquid refrigerant into low-pressure evaporators. Steam power plants throttle steam flow to regulate turbine inlet pressures and control plant output. Pipeline gas transmission systems experience pressure drops that require understanding throttling thermodynamics. Listing only heat exchange absence ignores the lack of work and internal energy constancy features. Stating only that work is zero provides an incomplete description of the multiple phenomena occurring. Claiming internal energy is unchanged ignores potential kinetic energy and specific volume variations.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. Carnot cycle efficiency attains maximum value for__________________?
Show answer Hide answer
Answer: A. reversible engine
Reversible engines operate without internal or external irreversibilities like friction or heat loss. The Carnot theorem proves that no engine can be more efficient than a reversible engine. Reversibility ensures maximum...
Q2. A perfect gas at 27°C undergoes constant pressure heating until its volume doubles, resulting in a final temperature of________________?
Show answer Hide answer
Answer: B. 327°C
Charles law states that volume is directly proportional to absolute temperature during constant pressure processes. Converting the initial temperature of 27 degrees Celsius to Kelvin gives a starting value of 300 Kelvin....
Q3. Given identical compression ratios and equal heat addition_________________?
Show answer Hide answer
Answer: A. Otto cycle is more efficient than Diesel cycle
For the same compression ratio and heat input, the Otto cycle is more efficient than the Diesel cycle. Heat addition in the Otto cycle occurs at constant volume rather than constant pressure. This thermodynamic differenc...
Q4. I kgf/cm2 is equal to________________?
Show answer Hide answer
Answer: C. 735.6 mm Hg
Standard conversion factors equate one kilogram-force per square centimeter to millimeter mercury pressure. Hydrostatic pressure calculations link density and height columns to establish this exact equivalence. One kgf/c...
Q5. A gas turbine cycle consists of___________________?
Show answer Hide answer
Answer: D. two isentropics and two constant pressures
A gas turbine cycle relies on the Brayton cycle, which features two constant pressure heat transfer stages. Compression and expansion phases within the turbine and compressor are modeled as ideal isentropic processes. Co...
Q6. The Brayton cycle is composed of the following four processes____________________?
Show answer Hide answer
Answer: D. two isentropics and two constant pres-sures
The Brayton cycle is composed of two reversible adiabatic and two constant-pressure processes. Isentropic compression and expansion form the work-producing and work-consuming stages. Heat addition and rejection occur at...