Concentrating temperature-sensitive substances requires an evaporator utilizing_______________?
Show answer Hide answer
Answer: A. Vacuum
Explanation
Operating under vacuum lowers the vapor pressure and corresponding boiling point of liquids. Lower boiling temperatures allow heat sensitive substances to concentrate without thermal degradation. Reducing system pressure decreases the required thermal energy input for solvent vaporization. Vapor pressure curves dictate that boiling occurs when system pressure equals saturation pressure. Heat sensitive materials include pharmaceuticals, biological broths, and delicate fruit juices. Evaporators utilize vacuum pumps and condensers to maintain low operating pressures continuously.
Sugar refineries utilize vacuum evaporation to prevent caramelization of sucrose solutions. Biochemical manufacturing plants concentrate enzyme solutions under strict low temperature vacuum conditions. Vacuum systems protect product quality and reduce steam energy consumption in processing plants. High pressure raises boiling points and causes severe thermal damage to sensitive compounds. High residence times increase thermal exposure and degrade temperature sensitive food products. Standard atmospheric evaporation requires excessive temperatures that destroy delicate organic solutes.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
Related questions
Q1. Beyond the Leidenfrost point on a boiling curve, heat flux rises with temperature drop because___________________?
Show answer Hide answer
Answer: C. Radiation becomes important
Past the Leidenfrost point, high surface temperatures cause radiation heat transfer to become dominant. A stable vapor blanket forms, making direct liquid contact impossible and boosting radiation across it. Thermal radi...
Q2. Heat flux in thermal circuits is analogous to _______________ in electrical circuits?
Show answer Hide answer
Answer: A. Current
In thermal-electrical analogies, heat flux corresponds directly to electrical current flowing through a circuit. Temperature difference acts as the thermal driving force, perfectly analogous to electrical voltage or pote...
Q3. Heat flux through multiple resistances in series corresponds to current flowing through multiple_____________________?
Show answer Hide answer
Answer: C. Resistances in series
Thermal resistances connected in series across a composite wall correspond directly to multiple electrical resistances in series. The total heat transfer rate through series layers experiences the same heat flux passing...
Q4. Thermal energy transfer via ____________ does not inherently require a material medium?
Show answer Hide answer
Answer: D. Radiation
Thermal radiation transfers energy through electromagnetic waves and can propagate perfectly through a complete vacuum. Unlike conduction and convection, radiation requires no atomic collisions or fluid motion to transpo...
Q5. When processing a cold viscous feed, backward feeding yields _____________ compared to forward feeding?
Show answer Hide answer
Answer: A. A higher capacity
Backward feeding introduces cold viscous feed into the final effect operating at lower temperatures. The feed flows toward the first effect where temperatures and pressures are highest. This high temperature exposure low...
Q6. Fourier’s law of heat conduction is applicable to _____________ boundaries?
Show answer Hide answer
Answer: C. Both A. and B.
Fourier’s law of heat conduction applies universally across both isothermal and non-isothermal boundary conditions. Temperature gradients exist locally within conducting media regardless of whether the boundary surfaces...