HVAC Systems

Chasm Division of HVAC (heating, ventilation, and air conditioning) refers to offering technology of indoor and automotive environmental comfort. HVAC system design is a major sub discipline of Chasm HVAC Team mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. Refrigeration is sometimes added to the field’s abbreviation as HVAC&R or HVACR, or ventilating is dropped as in HACR (such as the designation of HACR-rated circuit breakers).

HVAC is important in the design of medium to large industrial and office buildings such as skyscrapers and in marine environments such as aquariums, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fresh air from outdoors.

Industrial Air conditioning and Ventilation system also for the Commercial establishment, Hotels, Malls, Ships, Chemical Plants, Pharmaceutical and Allied Industry

Type of Air Conditioning System

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1. Direct Expansion Type of system

  • Room Air conditioner with Split/Cassette Air Conditioning system
  • Air/Water cooled Duct able Air conditioning system
  • Air/Water cooled Package Air Conditioning system
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2. Chilled Water Air conditioning system

  • Constant Volume Chilled water pumping system

A constant flow system is the simplest chilled water distribution scheme. Here, a set of constant speed pumps distributes fixed quantity of water at all times and the temperature varies to meet the load. The system uses 3-way control valves at air handler coils that allow some water to bypass the cooling coil during part load conditions. At low loads, the chilled water flow through the cooling coil is restricted (in response to supply air temperatures to the space) but the total quantity returned to the chiller remains constant.

  • Constant Primary/Variable Secondary Chilled water pumping system

In primary/secondary systems, water flows through the chiller primary loop at a constant rate, and water flows through the secondary loop, which serves air handlers or fan coils, at a variable rate. The constant speed pumps in secondary circuit are replaced with “variable speed” pumps. The speed of the secondary pumps is determined by a controller measuring differential pressure (DP) across the supply-return mains or across the selected critical zones. The decoupled section isolates the two systems hydraulically.

Also the system uses two-way valves in the air handlers that modulate secondary loop flow rate with load requirements. During light load condition, the 2-way control valves will close (partially or fully) in response to load conditions, resulting in pressure rise in the secondary chilled water loop. A differential pressure sensor measures the pressure rise in the secondary loop and signals variable frequency drive of secondary pumps to alter the speed (flow).

Primary-secondary variable-flow systems are more energy efficient than constant-flow systems, because they allow the secondary variable-speed pump to use only as much energy as necessary to meet the system demand.

  • Variable Primary Flow Chilled water pumping System

In a variable primary flow (VPF) system, chilled water flow is allowed to vary throughout the loop, including the chiller evaporators. In this system, the secondary pumps are eliminated, the primary pumps provide variable flow to supply system demand to the extent tolerated by the chillers, and the decoupling bypass of the primary/secondary system has been replaced by a bypass with a normally closed control valve that opens only to maintain minimum flow through active chillers.

The function of the bypass line VPF arrangement should not be confused with that of the de-coupler of primary/secondary arrangement. The bypass in this case is a smaller pipe sized for the minimum flow of the largest chiller. It contains a normally closed control valve that modulates open only when the low flow limit is reached.

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3. VRF/VRV Air conditioning system

VRF stands for Variable Refrigerant Flow. This Air Conditioning System comprises of different numbers of air handling units which are connected to an external condensing unit. As a result of this, the refrigerant flow can be varied either by using an inverter controlled variable speed compressor or using more than one compressor. It can be used in the buildings in order to save in energy, installation space as well as maintenance cost. The cooling capacity is very high and the overall consumption of power is not very high.