solar

1. TOPIC:
Solar Drying and Solar Cooling
DEPARTMENT OF ELECTRICALAND ELECTRONICS
ENGINEERING
Prepared by : D. SIVARAJ AP/EEE
1

2. Solar Dryer
Drying is a simple process of excess water (moisture) removal
from a natural or an industrial product.
Drying is an energy intensive process. (long preservation)
The purpose of drying an agricultural product is to reduce its
moisture content to a level that prevents its deterioration.
To slow down the action of enzymes, bacteria, yeasts and
molds.
This enable the food to be stored and preserved for long time
with out spoilage.

3. Solar Dryer
Crops are very sensitive to the drying conditions.
Drying must be performed in a way that does not seriously
affect their color, flavor, texture or nutritional value.
Temperature is major importance.

4. Solar Dryer
Solar dryer use air collectors to collect solar energy.
Two process:
 1. Is a heat transfer to the product using energy from the
heating source.
2. Is a mass transfer of moisture from the interior of the
product to its surface and from surface to the surrounding
air, in the form of water vapor.

5. When the pool of moisture on the surface is depleted and water can no longer
diffuse to the surface to maintain the constant rate of removal, we enter the falling
rate drying period.

13. Thank You

14. TOPIC:
Solar Cooling
DEPARTMENT OF ELECTRICALAND ELECTRONICS
ENGINEERING
Prepared by : D. SIVARAJ AP/EEE
14

15. Solar cooling
 In recent years, demonstration projects have shown the
potential to use solar thermal energy to drive those
chillers. Because most of the available thermal chillers
have large cooling capacities (often several hundred
KW), the focus of R &D was largely on developing
smaller cooling units as well as to improve the system
design.
 About 100 systems have been installed in Europe and
several are offering solar cooling solutions as part of
their product and service portfolio.

16. Why Solar cooling?
 Dramatic increase of air conditioning
 Cost of energy
 Issues related to environmental pollution
 Due to energy production
 Due to the use of CFC’s and HCFC’s
 Matched demand with source availability
 Crucial for improving life standards in developing
countries

17. Absorption type
 How does absorption chiller works?
 Absorption chillers use solar heat energy instead of
mechanical energy to provide cooling.
 A thermal compressor consists of an absorber, a generator,
a pump, and a throttling device, and replace the mechanical
vapor compressor
 Refrigerant vapor from the evaporator is absorbed by a
solution mixture in the absorber. This solution is then
pumped to the generator. There the refrigerant re vaporizes
using a waste steam heat source. The refrigerant- depleted
solution then returns to the absorber via a throttling
device.

18.  Conversion of Solar Radiation into Cooling or Air-conditioning
 1. Open Cycle Heat Transformation Thermal Process:
 Liquid Absorber usually water
 Solid Absorber usually silica gel
 2. Closed Cycle Heat Transformation Thermal Process:
 Liquid Absorption process using water/lithium-bromide or
water/ammonia solutions
 Solid Adsorption using silica gels, salts or ammonia activated carbon
 3. Thermo-mechanical Process:
 Vapour Compression
 Rankine Cycle

19. Basic Solar Cooling System

20. Absorbents commonly used
 The two most common refrigerant/absorbent mixtures used in
absorption chillers are
 Water/lithium bromide
 Ammonia/water

21. Components of a Solar cooling Systems
 A solar cooling installation consists of a typical solar
thermal system made up of
 Solar collectors
 Storage tank
 Control unit
 Pipes and pumps
 Thermally driven cooling machine- chillers.

22. Vapour compression

23. LiBr-H2O system

24. NH3-H2O Coolers

25. Thank You