Air Conditioning Systems: Introduction
66 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the main function of an air conditioning plant?

  • Transferring energy from the conditioned space (correct)
  • Acting as a heat source in summer systems
  • Supplying latent heat to the space in winter
  • Acting as a heat sink in winter systems

    • Why is a thermal distribution system necessary in an air conditioning system?

  • To act as a heat source
  • To increase energy consumption
  • To introduce fresh air into the conditioned space (correct)
  • To reduce Indoor Air Quality (IAQ)

    • Which factor does NOT influence the selection of an air conditioning system?

  • Type of refrigerant used (correct)
  • Required system reliability and flexibility
  • Initial and running costs
  • Maintainability

    • In summer systems, what role does the air conditioning plant play?

    <p>Acting as a heat sink</p> Signup and view all the answers

    What type of heat has to be supplied to the space in winter?

    <p>Sensible and latent heat</p> Signup and view all the answers

    Apart from energy transfer, what is another important function of the thermal distribution system?

    <p>Maintaining Indoor Air Quality (IAQ)</p> Signup and view all the answers

    What is the advantage of variable air volume (VAV) systems over constant volume systems?

    <p>Reduced power consumption in perimeter zones</p> Signup and view all the answers

    Why can there be problems with ventilation and indoor air quality in very low load situations in variable air volume systems?

    <p>The flow rate is too low for proper air distribution</p> Signup and view all the answers

    What is a potential difficulty in balancing dampers in variable air volume systems?

    <p>Widely varying airflow rates</p> Signup and view all the answers

    How do dual duct, constant volume systems provide both cooling and heating to different zones?

    <p>By mixing cold and hot air streams in mixing boxes</p> Signup and view all the answers

    Why does the dual duct system occupy more space compared to other systems?

    <p>Need for larger ducts due to higher airflow rates</p> Signup and view all the answers

    What allows dual duct systems to maintain proper indoor air quality and room air distribution?

    <p>Total airflow rate variation</p> Signup and view all the answers

    In outdoor air control in all air systems, why are the exhaust and outdoor air dampers controlled in unison?

    <p>For building pressurization or de-pressurization purposes</p> Signup and view all the answers

    How can energy efficiency be improved in dual duct systems during cold weather?

    <p>Shutting down the cooling coil</p> Signup and view all the answers

    What is the main difference between dual duct, constant volume systems and dual duct, variable air volume systems?

    <p>Constant airflow rate to each zone vs. airflow rate reduction based on load</p> Signup and view all the answers

    In single duct systems, what is the function of the supply fan?

    <p>Control the amount of cooling or heating provided in the coils</p> Signup and view all the answers

    What is the primary purpose of a humidistat in single zone air conditioning systems?

    <p>Measure humidity ratio and control humidifier</p> Signup and view all the answers

    What differentiates dual duct systems from single duct systems in air conditioning?

    <p>They use separate supply ducts for hot and cold air</p> Signup and view all the answers

    What distinguishes single zone systems from multiple zone systems in air conditioning?

    <p>Control based on temperature measured at a single point</p> Signup and view all the answers

    What is a characteristic feature of constant volume air conditioning systems?

    <p>Maintaining a constant volumetric flow rate of supply air</p> Signup and view all the answers

    What happens to return air from the conditioned space in all air systems?

    <p>It is conveyed back to the A/C plant for further processing</p> Signup and view all the answers

    How does an all water system differ from an all air system in air conditioning classification?

    <p>It uses water instead of air as the media for thermal distribution</p> Signup and view all the answers

    'Dual duct variable volume systems' are distinguished by their ability to:

    <p>Provide variable airflow rates based on demand</p> Signup and view all the answers

    What is a defining characteristic of unitary refrigerant-based systems in air conditioning classification?

    <p>They rely on refrigerant as the main media for thermal distribution</p> Signup and view all the answers

    What differentiates 'constant volume, multiple zone systems' from 'variable volume systems'?

    <p>Their adaptability to regulate airflow based on zones' demands</p> Signup and view all the answers

    What percentage of supply air flow rate is typically required for ventilation in the described system?

    <p>10%</p> Signup and view all the answers

    In what temperature range is it recommended to use 100% outdoor air in the air conditioning system?

    <p>13°C to 24°C</p> Signup and view all the answers

    What is a disadvantage of all air systems mentioned in the text?

    <p>Balancing air in large systems could be difficult</p> Signup and view all the answers

    What type of buildings may find it difficult to provide air conditioning using all air systems due to space constraints?

    <p>High-rise buildings</p> Signup and view all the answers

    In all water systems, what happens when cooling is required in the conditioned space?

    <p>Cold water is circulated</p> Signup and view all the answers

    What type of system is used for either cooling only or heating only application, but cannot be used for simultaneous cooling and heating?

    <p>2-pipe system</p> Signup and view all the answers

    What does a 2-pipe system in all water systems consist of?

    <p>Two pipes</p> Signup and view all the answers

    How is the flow rate of hot or cold water to the conditioned space controlled?

    <p>By the zone thermostat</p> Signup and view all the answers

    Which component is responsible for cooling and dehumidifying the air in a fan coil unit?

    <p>Finned tube cooling coil</p> Signup and view all the answers

    What is the purpose of a pressure relief valve (PRV) in the water line?

    <p>Maintaining balanced flow rate</p> Signup and view all the answers

    In a 4-pipe system, how many supply pipelines are there for hot and cold water?

    <p>Two each</p> Signup and view all the answers

    Which component of the fan coil unit is responsible for drawing warm air from the conditioned space?

    <p>Fan</p> Signup and view all the answers

    How is heat transfer primarily achieved in a convector?

    <p>By natural convection</p> Signup and view all the answers

    What can be used to control the capacity of a fan coil unit?

    <p>Controlling both air flow rate and water flow rate</p> Signup and view all the answers

    What is the main difference between coil control and face-and-bypass control in a single zone system?

    <p>The method of controlling zone humidity</p> Signup and view all the answers

    In a single duct, single zone system, which space type is suitable for applications of constant volume systems?

    <p>Laboratories with precise control requirements</p> Signup and view all the answers

    What is a disadvantage of single duct, multiple zone, constant volume systems with reheat coils?

    <p>High energy consumption for cooling and reheating</p> Signup and view all the answers

    Why might face-and-bypass control be preferred over coil control in a single zone system?

    <p>It allows for more precise control of zone humidity</p> Signup and view all the answers

    What type of systems are suitable for large buildings with several zones of different cooling/heating requirements?

    <p>Single duct, constant volume, multiple zone systems</p> Signup and view all the answers

    What is a key advantage of using single duct, multiple zone, constant volume systems with reheat coils?

    <p>Ability to control temperature and humidity accurately</p> Signup and view all the answers

    What prevents simultaneous cooling and heating in single duct, multiple zone systems with reheat coils?

    <p>The inability to switch off any reheat coils</p> Signup and view all the answers

    What makes single duct, multiple zone, constant volume systems with reheat coils unsuitable for energy-efficient cooling?

    <p>Requirement to first cool and then heat the air</p> Signup and view all the answers

    What is a benefit of using face-and-bypass control over coil control in a single zone system?

    <p>More precise humidity control</p> Signup and view all the answers

    In single duct, variable air volume (VAV) systems, what is the main purpose of the cooling and dehumidifying coil (CC)?

    <p>To cool and dehumidify the air to a set level</p> Signup and view all the answers

    What is one advantage of air-water systems over all air systems regarding space requirements?

    <p>They require less space because the primary airflow is less.</p> Signup and view all the answers

    What type of system allows for simultaneous cooling and heating?

    <p>Air-water systems</p> Signup and view all the answers

    What is the primary air responsible for in an air-water system?

    <p>Providing ventilation</p> Signup and view all the answers

    What is a disadvantage of air-water systems related to controlling the conditioned spaces?

    <p>The primary air cannot be shut down in unoccupied spaces.</p> Signup and view all the answers

    Why do unitary refrigerant based systems vary in capacity and type?

    <p>To cater to different cooling needs and conditioned spaces.</p> Signup and view all the answers

    Which component eliminates the need for a separate ventilation system in an air-water system?

    <p>Primary air</p> Signup and view all the answers

    What is a common feature of unitary refrigerant based systems?

    <p>They consist of separate air conditioning units with individual refrigeration systems.</p> Signup and view all the answers

    What type of buildings are most suitable for all water systems using fan coil units?

    <p>Office buildings</p> Signup and view all the answers

    What is the purpose of the secondary water lines in air-water systems?

    <p>Heating the conditioned space</p> Signup and view all the answers

    Why are fan coil units used in air-water systems?

    <p>To help control both primary air and secondary water.</p> Signup and view all the answers

    What can happen if ventilation in an air-water system relies on opening windows?

    <p>Dependency on wind and stack effects</p> Signup and view all the answers

    In what type of buildings are air-water systems typically used?

    <p>Exterior buildings with large sensible loads.</p> Signup and view all the answers

    Why is draining condensate water considered messy in air conditioning systems?

    <p>It creates health problems if not drained properly</p> Signup and view all the answers

    What is a potential issue related to the primary air in air-water systems?

    <p>Its supply cannot be shut down in unoccupied areas.</p> Signup and view all the answers

    What is a notable advantage of unitary refrigerant based systems?

    <p>They are factory assembled and tested as per standard specifications.</p> Signup and view all the answers

    Why are fan coil units used in air-water systems for individual zone control?

    <p>To control both primary air and secondary water flow rates.</p> Signup and view all the answers

    What is a limitation of unitary refrigerant based systems compared to other types of systems?

    <p>They are not suitable for perimeter zones only.</p> Signup and view all the answers

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser