Heat Load Calculation for AC Sleeper Coach
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Questions and Answers

What is the coefficient of heat transfer for the roof of the AC coach?

  • 0.615
  • 0.65 (correct)
  • 0.72
  • 1.94

    • How much is the temperature difference (T.D.) considered for end portions of the coach?

  • 5°C lower than other parts
  • Same as other parts
  • 2°C higher than other parts
  • 3°C lower than other parts (correct)

    • What is the outside dry bulb temperature (DBT) in the given conditions?

  • 30°C
  • 25°C
  • 40°C
  • 45°C (correct)

    • Which coefficient reflects the heat transfer through windows due to solar gain?

    <p>1.94 (A)</p> Signup and view all the answers

    What is the target relative humidity (RH) for inside conditions when fully loaded?

    <p>40% (B)</p> Signup and view all the answers

    What is the outside wet bulb temperature (WBT) given in the conditions?

    <p>25°C (C)</p> Signup and view all the answers

    What is the grains difference (G.D.) in the specified outside conditions?

    <p>26 (A)</p> Signup and view all the answers

    What is the internal temperature to be maintained according to the specifications?

    <p>20°C (A)</p> Signup and view all the answers

    Which component has the highest coefficient of heat transfer in the AC coach?

    <p>Window (Conduction) (B)</p> Signup and view all the answers

    What does RDSO specification No. TRC-1-72 primarily address?

    <p>Air conditioning capacity requirements (C)</p> Signup and view all the answers

    What is the total quantity of ventilating air required for 46 passengers per minute?

    <p>16.1 m3/minute (B)</p> Signup and view all the answers

    What is the heat transfer from fluorescent lights and incandescent lamps per watt?

    <p>3.4 BTU/Watt/Hr (B)</p> Signup and view all the answers

    What is the area of the side wall excluding windows?

    <p>25.239 M2 (A)</p> Signup and view all the answers

    How many BTU per hour does 1 Ton of refrigeration equate to?

    <p>12000 BTU/Hr (B)</p> Signup and view all the answers

    What is the total sensible heat per passenger in BTU per hour?

    <p>205 BTU/Hr (D)</p> Signup and view all the answers

    What is the height of the A.C. portion of the coach?

    <p>2.03 M (B)</p> Signup and view all the answers

    What is the calculated area of the roof?

    <p>49.324 M2 (C)</p> Signup and view all the answers

    What is the wattage of a carriage fan considered for calculations?

    <p>29 W (D)</p> Signup and view all the answers

    What is the area of the end partitions in square meters?

    <p>6.17 M2 (C)</p> Signup and view all the answers

    How much latent heat per passenger is registered in BTU per hour?

    <p>195 BTU/Hr (D)</p> Signup and view all the answers

    What is the total heat gain due to electrical appliances calculated in BTU/Hr?

    <p>7361.3 BTU/Hr (C)</p> Signup and view all the answers

    What is the final total of heat gain from all sources in BTU/Hr?

    <p>88815 BTU/Hr (C)</p> Signup and view all the answers

    How many tons of refrigeration capacity does the system have based on the gross total heat gain?

    <p>7.4 TR (B)</p> Signup and view all the answers

    What is the conversion factor used to convert watts to BTU/Hr?

    <p>3.4 BTU/Hr (C)</p> Signup and view all the answers

    Which of the following contributes the most heat gain in BTU/Hr?

    <p>Blower fan (B)</p> Signup and view all the answers

    What is the heat gain due to infiltration when derived from a percentage of the total heat gain?

    <p>8074.1 BTU/Hr (B)</p> Signup and view all the answers

    What is the equivalent K.Cal/Hr for the total calculated heat gain?

    <p>22371.56 K.Cal/Hr (B)</p> Signup and view all the answers

    What is the calculated heat gain from a 20W fluorescent light in BTU/Hr?

    <p>2448 BTU/Hr (B)</p> Signup and view all the answers

    What is the contribution in BTU/Hr from incandescent lamps based on the provided wattage?

    <p>816 BTU/Hr (C)</p> Signup and view all the answers

    What is the total heat gain due to conduction in the A.C. compartment?

    <p>9862.954 BTU/Hr (C)</p> Signup and view all the answers

    How much heat gain is attributed to solar heat according to the calculations?

    <p>12972.069 BTU/Hr (B)</p> Signup and view all the answers

    What formula is used to calculate heat gain due to passengers?

    <p>S.H. + L.H. = 400 x No.of passengers (C)</p> Signup and view all the answers

    What value did the heat gain due to ventilation calculate to?

    <p>22096.67 BTU/Hr (D)</p> Signup and view all the answers

    Which material contributes the least heat gain due to conduction?

    <p>End partition (D)</p> Signup and view all the answers

    Which type of light has the highest number in the A.C. compartment?

    <p>Fluorescent lights (B)</p> Signup and view all the answers

    How much is the heat gain from the roof calculated to?

    <p>2545.61 BTU/Hr (C)</p> Signup and view all the answers

    What method is utilized to calculate heat gain due to conduction?

    <p>A x K x TD x 3.97 (C)</p> Signup and view all the answers

    For a total of 46 passengers, what is the total heat gain due to passengers?

    <p>18400 BTU/Hr (C)</p> Signup and view all the answers

    How is the heat gain due to ventilation calculated?

    <p>S.H. = 1.08 x Q x TD x 9/5 (A)</p> Signup and view all the answers

    What is the total heat gain due to conduction from all sources in BTU/Hr?

    <p>9862.954 BTU/Hr (B)</p> Signup and view all the answers

    Which component contributes the highest solar heat gain in BTU/Hr?

    <p>Window (A)</p> Signup and view all the answers

    How is the total heat gain due to passengers calculated?

    <p>400 x Number of passengers (C)</p> Signup and view all the answers

    What formula is utilized to compute the heat gain due to ventilation?

    <p>1.08 x Q x TD x 9/5 (A)</p> Signup and view all the answers

    What is the contribution of solar heat gain from the roof in BTU/Hr?

    <p>1342.81 BTU/Hr (A)</p> Signup and view all the answers

    What is the total heat gain from ventilation calculated to?

    <p>22096.67 BTU/Hr (D)</p> Signup and view all the answers

    Which of the following is NOT considered in the total heat gain calculation?

    <p>Radiant heat gain (B)</p> Signup and view all the answers

    What is the calculated heat gain due to the floor in BTU/Hr?

    <p>2641.62 BTU/Hr (D)</p> Signup and view all the answers

    What is the value of sensible heat induced by 46 passengers in BTU/Hr?

    <p>18400 BTU/Hr (B)</p> Signup and view all the answers

    Calculate the total volume of ventilating air required for 46 passengers in cubic feet per minute (CFM).

    <p>568.33 CFM (B)</p> Signup and view all the answers

    What is the increase in solar temperature difference (TDS) across the roof compared to the side wall?

    <p>1.55°C (A)</p> Signup and view all the answers

    Given the heat transfer from fluorescent lights at 3.4 BTU/Watt/Hr, how much heat is transferred from a single 24W fluorescent tube?

    <p>81.6 BTU/Hr (C)</p> Signup and view all the answers

    What is the total sensible heat gain from 46 passengers based on the given data?

    <p>14030 BTU/Hr (C)</p> Signup and view all the answers

    What is the collective area of windows per side wall given that each window has an area of 0.3416 m^2 and there are 16 windows?

    <p>5.466 m^2 (B)</p> Signup and view all the answers

    Considering the latent heat per passenger is 195 BTU/Hr, calculate the total latent heat for 46 passengers.

    <p>8970 BTU/Hr (D)</p> Signup and view all the answers

    How much heat transfer results from 2 fluorescent tube lights, considering each is 24 W?

    <p>163.2 BTU/Hr (A)</p> Signup and view all the answers

    What is the total area of the side wall excluding windows calculated from the provided data?

    <p>25.239 m^2 (B)</p> Signup and view all the answers

    Which coefficient of heat transfer is responsible for conduction through windows?

    <p>1.94 (D)</p> Signup and view all the answers

    If 1 Ton of refrigeration equals 12000 BTU/Hr, how much refrigeration is needed for a total heat gain of 48000 BTU/Hr?

    <p>4 Tons (A)</p> Signup and view all the answers

    What is the assumed temperature difference (T.D.) for the general areas of the coach compared to the end portions?

    <p>3°C lower for end portions (A)</p> Signup and view all the answers

    How much total area does the roof of the AC portion of the coach cover based on its dimensions?

    <p>49.324 m^2 (B)</p> Signup and view all the answers

    Which of the following parameters contributes to determining the air conditioning plant capacity for a sleeper coach?

    <p>Volume of fresh air per passenger (A)</p> Signup and view all the answers

    What is the purpose of the coefficient of heat transfer (k) values provided for various parts of the coach?

    <p>To calculate load requirements (A)</p> Signup and view all the answers

    In the context of air conditioning for the sleeper coach, which condition relates to the moisture grains specified?

    <p>Relative humidity control (A)</p> Signup and view all the answers

    What is the target dew point temperature (DBT) for the inside conditions of the AC sleeper coach?

    <p>20°C (C)</p> Signup and view all the answers

    Which value correlates with the solar temperature difference (T.D.S) when determining air conditioning requirements?

    <p>20°C (B)</p> Signup and view all the answers

    Under the specified conditions, what humidity level is considered acceptable for passenger comfort?

    <p>40% (B)</p> Signup and view all the answers

    How is the heat gain through windows characterized, according to the coefficient of heat transfer?

    <p>It contributes significantly to overall heat gain (D)</p> Signup and view all the answers

    What is the value of the coefficient of heat transfer for the roof of the AC coach?

    <p>0.65 (C)</p> Signup and view all the answers

    What is the total heat gain in BTU/Hr from all methods including appliances, infiltration, and other sources combined?

    <p>88815 BTU/Hr (D)</p> Signup and view all the answers

    How much heat gain is attributed to the infiltration at 10% of the total heat gain?

    <p>8074.1 BTU/Hr (D)</p> Signup and view all the answers

    What is the refrigeration capacity in tons resulting from a total heat gain of 88815 BTU/Hr?

    <p>7.4 TR (B)</p> Signup and view all the answers

    What is the total heat gain in BTU/Hr due to electrical appliances when summed?

    <p>7361.3 BTU/Hr (D)</p> Signup and view all the answers

    What is the heat gain in BTU/Hr from a blower fan operating at 0.65 HP?

    <p>3308.5 BTU/Hr (B)</p> Signup and view all the answers

    How is the heat gain from fluorescent lights calculated given their wattage?

    <p>Wattage x 3.4 BTU/Hr (B)</p> Signup and view all the answers

    What is the combined heat gain in BTU/Hr from fluorescent and incandescent lamps?

    <p>2033.78 BTU/Hr (B)</p> Signup and view all the answers

    How much heat gain is derived from a 15W incandescent lamp?

    <p>205.54 K.Cal/Hr (B)</p> Signup and view all the answers

    What factor is used to convert wattage to BTU/Hr?

    <p>3.4 (B)</p> Signup and view all the answers

    What is the calculated heat gain from each fluorescent light rated at 20W?

    <p>2448 BTU/Hr (A)</p> Signup and view all the answers

    Flashcards

    Heat Load Calculation (AC Coach)

    Determining the required AC plant capacity for an air-conditioned coach, considering varying ambient conditions.

    Ambient Temperature Difference (T.D.)

    The difference between the inside and outside ambient temperatures of the coach.

    Solar Temperature Difference (T.D.S)

    Difference in temperature due to solar heat gain on the coach.

    Heat Transfer Coefficient (k)

    A measure of how quickly heat transfers through a material.

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    Window Heat Transfer Coefficient (U)

    Specific heat transfer coefficient for windows.

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    RDSO Specification No. TRC-1-72

    Standard comfort conditions and requirements for air-conditioned coaches.

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    Coach Internal Conditions

    Internal temperature, humidity, and moisture content.

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    Coefficient of Heat Transfer (Wall/End)

    Heat transfer rate through wall and end partitions.

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    Coach Internal Temp (Design)

    Desired inside temperature for passenger comfort.

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    End Partition Temperature Difference

    3°C lower than other parts, due to adjacent non-AC space.

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    Heat Gain in AC Compartment

    The total heat entering the air-conditioned compartment from various sources like conduction, solar radiation, passengers, and ventilation.

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    Conduction Heat Gain

    Heat transferred through the walls, roof, floor, and windows of the AC compartment due to a temperature difference between inside and outside.

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    Solar Heat Gain

    Heat absorbed by the AC compartment directly from sunlight.

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    Passenger Heat Gain

    Heat generated by the passengers inside the AC compartment, mainly due to their body temperature.

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    Ventilation Heat Gain

    Heat brought into the AC compartment by air being drawn in for ventilation.

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    Temperature Difference (TD)

    The difference in temperature between the inside of the AC compartment and the outside ambient temperature.

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    BTU (British Thermal Unit)

    A unit of energy, used to measure heat gain in the AC compartment.

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    Fresh Air Requirement

    0.35 cubic meters of fresh air per passenger per minute is needed in non-smoking compartments.

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    Ventilating Air Quantity (Q)

    The total amount of ventilating air (for 46 passengers) required per minute. Calculated as 16.1 m³/minute in this case.

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    Electrical Appliance Wattages

    Wattage values for various electrical appliances (e.g., fluorescent tubes, incandescent lamps, fans) used in the calculation of heat loads.

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    Heat Transfer (Equipments)

    Equipment and fan heat transfer in BTUs per horsepower per hour (HP/Hr).

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    Heat Transfer (Lights)

    Heat transfer from fluorescent lights and incandescent lamps in BTUs per Watt per hour.

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    Sensible Heat/Passenger

    The amount of heat energy a passenger produces that contributes to the ambient temperature.

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    Latent Heat/Passenger

    The amount of heat energy absorbed or released by a passenger in the form of perspiration or humidity changes.

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    Refrigeration Capacity (Ton)

    A measure of cooling capacity in BTUs per hour (BTUs/Hr).

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    Coach Dimensions

    Measurements pertinent to a specific coach, such as length (A), width of the roof (B), width of the floor (C), height (D), and the area of various surfaces (side walls, roof, floor, windows, end partitions).

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    Heat Load Calculation

    Determining the amount of heat that needs to be removed from a space (like a train coach) to maintain a comfortable temperature.

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    Coach Internal Temperature (Design)

    The target temperature inside the train coach for passenger comfort.

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    Fresh Air Requirement (smoking v.s. non-smoking)

    Non-smoking compartments require 0.35 cubic meters of fresh air per passenger per minute. Smoking compartments require more.

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    Solar Temp. Difference (TDS)

    The difference in temperature between the inside and outside of the air-conditioned coach due to solar heat gain.

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    Heat Gain

    The total heat entering the air-conditioned compartment from various sources like conduction, solar radiation, passengers, and ventilation.

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    Sensible Heat

    The amount of heat energy a passenger produces that contributes to the ambient temperature.

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    Latent Heat

    The amount of heat energy absorbed or released by a passenger in the form of perspiration or humidity changes.

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    Study Notes

    Heat Load Calculation of AC Sleeper Coach

    • AC coaches need to be sized based on various conditions (temperature, latitude, passenger load).
    • Assumptions are made about the working conditions to determine the capacity of the AC plant.
    • Standards for comfort (like fresh air per passenger) and heat transfer coefficients for coach parts are specified.

    Abbreviations and Constants

    • T.D.: Ambient temperature difference
    • T.D.S.: Solar temperature difference
    • K: Coefficient of heat transfer (K cal/Hr/m²/°C)
    • U: Coefficient of heat transfer for windows due to solar gain
    • G.D.: Grains difference

    Coefficients of Heat Transfer (k)

    • Wall and end partitions: 0.615 k-Cal/Hr/m²/°C
    • Roof: 0.65 k-Cal/Hr/m²/°C
    • Floor: 0.72 k-Cal/Hr/m²/°C
    • Windows (conduction): 1.94 k-Cal/Hr/m²/°C
    • Windows (U-value): 5.34 k-Cal/Hr/m²/°C

    Operating Conditions

    • Outside conditions: 45°C, 25°C, 82% RH, 52 Moisture grains
    • Inside conditions: 25°C, 40°C, 56% RH, 26 Moisture grains
    • Temperature difference (T.D.): 20°C
    • Grain difference(G.D.): 26

    Other Calculations

    • Fresh air for non-smoking compartments: 0.35 m³/passenger/minute
    • Total fresh air for 46 passengers: 16.1 m³/minute
    • 2 Fluorescent tubes (24W each)
    • 16 incandescent lamps (15W each)
    • 8 Fans (29W each)

    Dimensions of AC Portion

    • Length of AC portion (A): 15.2m
    • Width of roof (B): 3.245m
    • Width of floor (C): 3.04m
    • Height of A.C. portion (D): 2.03m
    • Area of side wall (A x D): 30.856 m²
    • Area of roof (A x B): 49.324 m²
    • Area of floor (A x C): 46.208 m²

    Heat Gain Calculations

    • Includes conduction, solar (for walls, roof, floor, Windows), Passengers' heat gain, ventilation heat gain, Electrical loads (fluorescent lights, incandescent lamps, Fans and blowers)

    • Extensive calculations for these parameters are provided in the text.

    Refrigeration Capacity

    • Final calculation determining the amount of refrigeration required by the coach, to maintain specified temperature conditions.
    • The result is expressed as a number of tons of refrigeration (TR), which is a common unit in AC system design.

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    Description

    This quiz covers the principles of heat load calculation specific to AC sleeper coaches. It includes various factors like ambient temperature, passenger load, and coefficients of heat transfer. Understanding these concepts is essential for effective HVAC design in railway coaches.

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