Air conditioning Fundamentals
The purpose of an air conditioning system is to transfer heat from lower temperature in the conditioned space to higher temperature ambient. The atmosphere is considered as a heat sink and heat is rejected directly from the heat exchanger in air-cooled systems or indirectly through cooling towers in water-cooled systems. This is achieved by increasing the temperature of the refrigerant above the ambient temperature and then dissipating heat into the atmosphere. This can be visualized as a temperature lift or pressure lift using the compressor. The lower the temperature lift, the lower is the work done and the lower is the energy consumed. The energy efficiency of an air conditioning system ia an outcome of multiple interdependent factors, such as the efficiency of the fan-motor combination, compressor and heat exchangers as a direct proportion, and can be increased by reducing the losses due to pressure drop in the refrigeration system, chilled water system and of air flow over in air-cooled condensers and evaporators.
Installation, Commissioning and service
(Ref: Ishrae Journal July Aug 2022)
A well designed efficient system, if not installed and commissioned properly, will end in poor performance. In cities, the urban heat index has to be considered before the selection of AC equipment. High-rise buildings have challenges in terms of heat stack effect and high wind velocity. Heat stack effect increases as we move higher due to the movement of air discharged from the air conditioner installed on lower floors. Also, if the wind is flowing against the discharged air flow of air conditioner, the net air-flow, flowing over the condenser reduces the impact on the performance. It is important to select the location of AC IDU/ODU after careful evaluation. Installation location should also be selected to ensure free flow of fresh air and avoid installation in basements or installation of multiple units in close proximity. Servicing is an important aspect to ensure that near design performance is maintained.
We, at Saarathi Projects, have a culture of sharing and learning through each – other’s experiences. We conduct regular meetings to train new members and discuss challanges faced at HVAC Projects site and steps taken to overcome them, to ensure desired Air conditioning outcomes. This makes us a learning and growing organization, ready to handle tough and uncertain situations during HVAC project execution stages.
HVAC Project cost estimation and performance
The selection of an HVAC system depends on various factors like application, space constraints, heat load conditions, occupancy, running costs, product availability, brand preferences and desired durability. Hence, similar spaces may require different HVAC design and solutions. The performance of an HVAC system is also an outcome of multiple factors like equipment efficiency, piping lengths, ventilation conditions, power supplies, cooling leakages, remote settings etc.