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HVACWhat is HVAC ? H- HeatingV-VentilationAC- Air Conditioningrefers to technology of indoor and automotive environmental comfort. It describes the process of treating air to control simultaneously its temperature, humidity, cleanliness, and distribution to meet the desired requirements of the occupants of the conditioned space.

Few people Think that HVAC is all about luxury, BUT.Need of special HVAC planning for hospitals

The environmental needs of the facilities and spaces in a hospital differ widely- A hospital has a range of very specialized rooms, and there are specialized IAQ considerations for each type of spaceInfection control and epidemic disease concerns are leading many hospitals to provide 100 percent outside air with no air recirculation, coupled with heat recovery technologies. Hospital air change rates contribute to their enormous energy consumptionIn this era of expensive energy and concerns about carbon emissions, design teams must balance energy demand, air quality, sealed envelopes, and pollutant source control.

The basic differences between hospitals and other buildingsThe need to restrict air movement in and between various areas,Ventilation and filtration to dilute and remove odors, airborne microorganisms, and hazardous chemical substances,Many areas that require 100% outdoor air with specified air changes,The need for different temperatures and humidy in areas for infection control, patient therapy and comfort,The design sophistication needed to permit accurate control of environmental conditions.Basics of HVAC Systems

Compressor Condenser Throttling deviceEvaporator 1 TR is the amount of heat to be extracted from the atmosphere for melting one metric ton of ice in 24 hours And1 ton of refrigeration (TR) equals to 12000 BTU/HR or 3025KCAL/HR

Classification of HVAC Systems Window AC

Window ACIn a typical split system, the condenser and compressor are located in an outdoor unit. The indoor unit consists of evaporator coil, fan motor and blower.Split AC

The window and split air conditioners are usually used for the small air conditioning capacities up to 5 tonsDX Ducted Packaged AC

DX -Centralized AC

The central air conditioning systems are used for where the cooling loads extend beyond 20 tons

DX -Centralized AC

Chilled Water -Centralized ACBrime water- 2-10 % salt

HVAC design and SelectionCOOLING AND HEATING LOAD CALCULATIONFACTORS OF HEAT GAIN IMPORTANCE OF COOLING LOAD CALCULATION

Considerations and Parameters

Cooling and Heating Load CalculationCooling load calculations are carried out to estimate the heat gain by the building in summer so as to arrive at required cooling capacities. Similarly Heating load calculations are carried out to estimate the cold gain by the building in winters so as to arrive at required heating capacities.

Cooling and Heating Load CalculationThe whole building cooling/Heating load is based on two types of loads: External load Internal load The load due to heat transfer through the envelope is called as external load, while all other loads are called as internal loads.20

T2T1 T1>T2 Factors of heat gain

Difference between outside temperature and inside temperature.

The type of construction and the amount of insulation is in your ceiling and walls.

The amount of shade in buildings windows, walls, and roof

The size of room

The amount of air leaks into indoor space from the outside

Factors of heat gain

No. of occupants

Activities and other equipment within a building

Amount of lighting in the room

IMPORTANCE OF COOLING LOAD CALCULATION

Provide information for equipment selection, system sizing and system design.

Provide data for evaluating the optimum possibilities for load reduction. This could be done either changing the material to be used in envelope or changing the orientation of some of the spaces or materials present in the building

Permit analysis of part loads as required for system design, operation & controlInformation about the additional partial loads required for the system design, operation and control also.

Factors Affecting the SelectionBudget Of ClientNeed of client Use of Space Depth of BeamPower AvailabilityWater AvailabilitySpace for Servicing

Types Of Chillers

Air Cooled

Water Cooled Chiller (Air - Cooled)

Air cooled chillers absorb heat from process water, and the heat is then transferred to the air around the chiller unit. This type of chiller system is generally used in applications where the additional heat discharges is not a factor. In fact, its often practical to use the excess heat to warm a plant during the winter, thus providing additional cost savings.

Air cooled chillers require less maintenance than water-cooled units, and they eliminate the need for a cooling tower and condenser water pump. However, since a wet surface will transfer heat better than a dry surface, an air-cooled chiller will tend to consume approximately 10% more power than a water-cooled unit.Chiller ( Water - Cooled )

Water cooled chillers absorb heat from process water and transfer it to a separate water source such as a cooling tower, river, pond, etc. Industrial water chillers are generally used for large capacity applications, where the heat generated by an air cooled water chiller creates a problem. They are also considered when a cooling tower is already in place, or where the customer requires optimum efficiency of power consumption.

Water cooled chillers require condenser water treatment to eliminate mineral buildup. Mineral deposits create poor heat transfer situations, which reduce the efficiency of the unit.Air Cooled Chilled Water System

Water Cooled Chilled Water System15- 20 years Life 20-30 years Life Depend on Ambient DB tempDepend on Ambient WB tempPackaged kind SystemAdditional pumps No cooling tower or may be a cooling towerCooling TowerAir Cooled Condensers consumes 30% more power than water CooledCompressor capacity drops by 10% for air cooled as compared to water cooled Air Cooled will always be a roof top UnitWater cooled may or may not be a Roof top unitR-134aR-123R-407CR-410AR-22Environment friendly refrigerants