Question

An air conditioning system is used to provide cooling for a small office building in the summer. Cool dry air (State 4) is supplied to the conditioned space (State 5) to balance the total cooling load (QT) for the space. Air exiting through return ducts is either recirculated or exhausted from the building. The recirculated air is mixed with a specified volume flow rate of outdoor air (State 1) to meet air quality requirements. The mixed air stream (State 2) is cooled to the dewpoint temperature (T2A) and dehumidified by the cooling system to a relative humidity of 100% (State 3). Finally, the air is reheated by a electric resistance coil heating system to the supply air conditions . Using the psychrometric chart, determine the following given the conditions below.

Answer 1

The question addresses the principles of thermodynamics in relation to air conditioning systems. It explains how air conditioners and refrigerators transfer heat from cooler to warmer environments and introduces the concept of the coefficient of performance (COP). A psychrometric chart can be used to analyze and understand the thermodynamic processes in HVAC systems.

Step-by-step explanation:

The question involves an understanding of the principles of thermodynamics, specifically how an air conditioning system operates to cool and dehumidify air in a building. Air conditioners and refrigerators operate on the same basic principle of heat transfer, requiring work (energy) to move heat from a cooler to a warmer environment.

In the description provided, the refrigeration cycle includes an electrically driven compressor that raises the temperature and pressure of a refrigerant, a condenser where the gas condenses to a liquid, and evaporator coils where the cooling of the environment takes place. The efficiency of these systems is often measured by the coefficient of performance (COP), which is the ratio of heat transfer to work input.

Understanding and calculating these processes often involves the use of a psychrometric chart, which assists in visualizing the interactions of air temperature, moisture content, and relative humidity, affecting the overall performance of air conditioning systems.