Presentation on HVAC: Heating Ventilation Air Conditioning

Transcription

1 Presentation on HVAC: Heating Ventilation Air Conditioning CHITKARA UNIVERSITY CHITKARA SCHOOL OF MECHANICAL ENGINEERING ;HARVINDER SINGH

2 HVAC Heating, Ventilation and Air Conditioning Provides comfort for people Allows humans to exist under adverse conditions.

3 Load Calculations Heating and Cooling Accuracy important! Design conditions Building shell load Internal load Ventilation load Infiltration Occupancy schedules

4 Refrigeration It is defined as the process of providing and maintaining a temperature well below that of surrounding atmosphere. In other words refrigeration is the process of cooling substance.

5 Air-Conditioning Principles Must be a transfer of heat for refrigerant to change state Liquid absorbs heat as changes to gas Vapor releases heat as changes to liquid

6 Heat Transfer Heat flows to anything with less heat Convection Heat rises Heat always flows from hot to cold Radiation Example: heat from the sun Evaporation Moisture absorbs heat as it is vaporized Example: perspiration

7 Refrigerators and heat pumps If the main purpose of the machine is to cool some object the machine is named as refrigerator If the main purpose of machine to heat a medium warmer than the surroundings, the machine is termed as heat pump.

8 Refrigerator and Heat pump Q R Work Input Heat Pump Warm Space Work Input Q R Refrig erator Cold Space

9 Types of Refrigerators Ice Refrigerators : Ice is kept in the cabinet of refrigerators and this acts as the refrigerating means. Air Refrigerators : Air is used as working agent in these types of refrigerators. Vapour Refrigerators: The working agents employed in this type of refrigerators are ammonia, CO 2, SO 2, freons etc.,

10 Applications of Refrigeration In chemical industries, for separating and liquefying the gases. In manufacturing and storing ice. For the preservation of perishable food items in cold storages. For cooling water. For controlling humidity of air manufacture and heat treatment of steels. For the preservation of tablets and medicines in pharmaceutical industries. For the preservation of blood tissues etc., For comfort air conditioning the hospitals, theatres, etc.,

11 Vapour Compression Refrigeration System

12 Vapour Compression Refrigeration System - Construction This system consists of a compressor, condenser, a receiver tank, an expansion valve and an evaporator. Compressor : Reciprocating compressors generally used. For very big plants centrifugal compressors directly coupled with high speed rotating engines (gas turbine) are used.

13 Vapour Compression Refrigeration System - Construction Compressor: For very big plants Centrifugal compressors directly coupled with high speed rotating engines (gas turbine) are used

14 Vapour Compression Refrigeration System - Construction Condenser : It is a coil of tubes made of copper. Receiver tank: It is the reservoir of liquid refrigerant. Expansion Valve: This is a throttle valve. High pressure refrigerant is made to flow at a controlled rate through this valve. Evaporator : It is the actual cooler and kept in the space to be cooled. The evaporator is a coil of tubes made of copper

15 EVAPORATOR TUBING

16 Vapour Compression Refrigeration System - Working Working : 1. The low pressure refrigerant vapour coming out of the evaporator flows into the compressor. 2. The compressor is driven by a prime mover. 3. In the compressor the refrigerant vapour is compressed. 4. The high pressure refrigerant vapour from the compressor is then passed through the condenser. 5. The refrigerant gives out the heat it had taken in the evaporator

17 Vapour Compression Refrigeration System - Working Working : 6. The heat equivalent of work done on it (w) on the compressor. 7. This heat is carried by condenser medium which may be air or water. 8. The high pressure liquid refrigerant then enters the expansion valve. 9. This valve allows the high pressure liquid refrigerant to flow at a controlled rate into the evaporator. 10. While passing though this valve the liquid partially evaporates.

18 Vapour Compression Refrigeration System - Working Working : 11.Most of the refrigerant is vapourised only in the evaporator, at a low pressure. 12. In the evaporator the liquid refrigerant absorbs its latent heat of vapourisation from the material which is to be cooled. 13. Thus the refrigerating effect is obtained. 14. Then the low pressure refrigerant enters the compressor and the cycle is repeated.

19 Layout of Domestic Refrigerator

20 Window Type Air Conditioner

21 Window Type Air Conditioner - Construction This is also called room air conditioner. This unit consists of the following. 1. A cooling system to cool and dehumidify the air involves a condenser, a compressor and a refrigerant coil. 2. A filter to any impurities in the air. The filter is made of mesh, glass wool or fibre. 3. A fan and adjustable grills to circulate the air. 4. Controls to regulate the equipment operation.

22 Humidity Low humidity Permits heat to be taken away from the human body Evaporation and perspiration High humidity Makes evaporation difficult People feel as comfortable at 79 F with 30% humidity as at 72 F at 90% humidity

23 AIR FILTERS Air filters Air cleaning and filtration Operating performance: Efficiency or effectiveness of dust removal Dust holding capacity Service life Types: low-, medium-, and high-efficiency filters

24 CLEAN ROOM CLASSIFICATION (ISO 14644)

25 THANKS