Question

Majority of HTST pasteurizers uses _________ heat exchangers with sections for regenerative heating and cooling.

• A. Plate heat exchanger
• B. Double pipe heat exchanger
• C. Shell and tubes heat exchanger
• D. Shell and coil heat exchanger

Hint:

Plate heat exchangers are highly suited for low-viscosity liquid foods because they offer compact designs, high thermal efficiency, and the ability to integrate regeneration sections easily.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
High-Temperature Short-Time (HTST) pasteurization is a continuous thermal process used to pasteurize liquid foods like milk and fruit juices.
The process requires rapid heating and cooling cycles, making the choice of heat exchanger critical for energy efficiency and product quality.

Step 2: Detailed Explation:
The Plate Heat Exchanger (PHE) is the primary heat exchanger design used in HTST pasteurizers:
- A PHE consists of a series of thin, corrugated metal plates packed together inside a frame, creating flow channels for the heating and cooling media.
- This design provides a large surface-to-volume ratio, resulting in high heat transfer coefficients and rapid heating and cooling.
- This rapid heat transfer is essential for meeting the short holding time requirements (\(72^\circ\text{C}\) for 15 seconds) of HTST pasteurization.
- In a continuous pasteurizer, the plate assembly is divided into three functiol sections: heating, cooling, and regeneration.
- In the regeneration section, incoming cold raw milk is preheated by the hot, pasteurized milk flowing in the opposite channel.
This heat exchange saves up to 90% of the heating energy and reduces the cooling load needed for fil chilling, making the process highly energy-efficient.
- Other configurations like double-pipe or shell-and-tube heat exchangers are less suited for high-capacity regeneration of low-viscosity liquids because of lower heat transfer surface areas and higher space requirements.

Step 3: Fil Answer:
The majority of continuous HTST pasteurizers utilize plate heat exchangers for efficient thermal processing and energy regeneration.
Hence, the correct option is (A).