9673204 Drying and Storage (มคอ.3)

Credits

3(2-2-5) credits (Lecture - Practice - Self-study)

Course Description

     Theory of drying, sun drying, principles of air flow, drying of agricultural products by heated air, moisture content determination, relationship of moisture and temperature, equilibrium moisture content, design of dryers storage

Lecture 1 – Importance and Theory of Drying (Handout 1)
Study Questions – Lecture 1
1. Why do agricultural materials dry?
2. How are natural drying and artificial drying different in terms
of process and control?
3. How is the moisture content of agricultural materials
determined?

 

Lecture 2-Psychrometrics (Handout 2)
Study Question – Lecture 2
1. What is psychrometrics, and why is it important in agricultural drying processes?
2. How are the psychrometric properties of air represented on a psychrometric chart?
3. How can the energy required for heating air and drying grain be determined using psychrometric principles?
4. How can psychrometric principles be applied to drying system?

 

Lecture 2.1 –Psychrometrics (Bonus!!!) (Handout 2.1)

Study Question – Lecture 2.1

1. Where can we access an online psychrometric calculator, and how do we use it?

 

Lecture 3–Flow Resistance Calculation and Fan Selection (Handout 3)

Study Questions – Lecture 3

1. Why is airflow resistance important in agricultural drying systems?
2. What factors contribute to pressure drop in grain beds and air ducts?
3. How can airflow resistance be calculated in drying systems?
4. How are fans selected based on airflow and pressure requirements?

 

Lecture 4–Moisture Content (Handout 4)
Study Questions – Lecture 4
1. What is equilibrium moisture content, and why is it important in drying and storage of agricultural products?
2. How is water activity related to equilibrium moisture content and product deterioration?
3. What is equilibrium relative humidity, and how does it relate to material moisture equilibrium?
4. How can equilibrium moisture content be determined experimentally?
5. Why are mathematical models used to predict equilibrium moisture content?

 

Lecture 5–Physical and Thermal Properties of Agricultural Materials (Handout 5)
Study Questions – Lecture 5
1. Why are physical properties important in dryer and silo design?
2. How do bulk density and porosity influence airflow?
3. What is the relationship between moisture content and density?
4. How do thermal properties affect drying time?
5. Why does shrinkage occur during drying?

 

Lecture 6–Solar Drying (Handout 6)
Study Questions – Lecture 6
1. Why is solar drying considered an important method for preserving agricultural products?
2. How does airflow occur in natural convection solar dryers?
3. What are the main differences between natural and forced convection solar dryers?
4. What types of solar dryer structures are commonly used, and how do they affect airflow performance?

 

Lecture 6.1–Solar Calculator (Bonus!!!) (Handout 6.1)
Study Questions – Lecture 6.1
1. Why does geographical location (Latitude and Longitude) affect the amount of solar energy received?
2. How can modern tools like the Global Solar Atlas simplify the assessment of solar drying potential?

 

Lecture 7–Drying and Types of Dryers for Fruits, Herbal Plants, and Cereal Grains (Handout 7)
Study Questions – Lecture 7
1. How do drying air conditions (temperature, relative humidity, and airflow) influence the drying rate and product quality of agricultural materials?
2. What are the effects of drying temperature on: Moisture migration Colour retention Chemical composition Nutritional value
3. Which drying technique is most appropriate for large-scale grain processing, and why?

 

Lecture 8–General Principles of Dryer Design (Handout 8)
Study Questions – Lecture 8
1. What factors must be considered when selecting a dryer?
2. How is airflow rate determined in bulk drying?
3. What components contribute to total pressure loss?
4. How is fan power calculated?
5. What are the main components of heat energy in drying systems?

 

Lecture 9–Principles of Agricultural Product Storage (Handout 9)
Study Questions – Lecture 9
1. Why is drying alone insufficient to ensure long-term storage stability of cereal grains?
2. How do temperature and relative humidity influence safe grain moisture content during storage?
3. Why is CO₂ concentration considered an important indicator of grain quality during storage?

 

Lecture 10 – Insect Infestation in Storage and Grain Aeration (Handout 10)
Study Questions – Lecture 10
1. What types of insect pests commonly attack stored grains?
2. How can insect infestation be evaluated during storage?
3. How is CO₂ concentration used to estimate insect population?
4. When should fumigation be applied in grain storage systems?
5. Why is aeration important after fumigation and during storage?

 

Lecture 10.1 – Chilled Aeration (Bonus!!!) (Handout 10.1)
Study Questions – Lecture 10.1
1. Why cooling stored grain matters?
2. What is chilled aeration?
3. When is chilled aeration especially useful?