INTRODUCTION TO HVAC

OBJECTIVES:

The main processes of heating ,ventilation and air conditioning. There are no calculation to be done. The ideas will be addressed.

INTODUCTION:

Heating, ventilation and air conditioning, HVAC is a huge field. HVAC systems include a range from the simplest hand-stoked stove, used comfort heating to the extremely reliable total air-conditioning systems found domestic marines and space shuttles. Cooling equipment varies from the small domestic unit to refrigeration machines that are 10,000times the size, which are used in industrial processes.

Depending on the complexity of the requirements, the HVAC designer must consider many more issues than simply keeping temperatures comfortable. I will introduce you to the fundamental concepts that are used by designers to make decisions

About system design, operation, and maintenance.

HISTORY OF HVAC:

For millennia, people have used fire for heating. Initially, the air required to keep the fire going ensured adequate ventilation for the occupants. However as central furnaces with piped stream or hot water become available for heating the need for separate ventilation become apparent. By the late 1880s,rules of thumb for ventilation design were developed and used in many countries.

In 1851 Dr. john gorrie was granted U.S patent 8080for a refrigeration machine.By two main uses were freezing meat for transport and making ice. Howevre, in the early 1900s there was a new initiative to keep buildings cool for confort. cooling the NEW YORK STOCK EXCHANGE IN 1902 was one of the first comfort Comfort cooling system .comfort cooling was called “air-conditioning”.

SCOPE OF MODERN HVAC:

Modern air conditioning is critical to almost every facet of advancing human activity. Although there have great advances in hvac, there are swveral areas where active research and debate continue.

Indoor air quality is one that directly affects us. In many countries of the world there is a rapid rise in asthmatics and increasing dissatisfaction with indoor-air –quality in buildings and planes.The causes and effects are extremely complex.A significant and engineering field has developed to investigate and address these issue.

Energy conservation is an ongoing challenge to find novel ways to reduce consumption in new and exiting building with out compromising comfort and indoor air quality. Energy requires significant cooperation between disciplines.

For example, electric lighting produces heat. When s system is in a cooling mode, this heat is an additional cooling load. conversely,when the system is In a heating mode, the lighting heat reduces the load on the building heating system. This interaction between lighting and HVAC is the reason that ASHRAE and the illumination engineering socity of north America (IESNA) joined forces to write the building energy convervation standard 90.1-2004, energy standard for building except low-rise residential buildings.

Greenhouse gas emissions and the destruction of the earth’s protective ozone layer are concerns that are stimulating research. New legislation and guidelines are evolving that encourage :recycling the use of new forms of energy;less energy usage;nad low polluting materials , particularly refrigerants. all these issues have a significant impact on building design, including HVAC system and the design codes