Heat Gain Calculation And Definition


Outer walls for air conditioning or heat gain calculations account, roofs, glass, heat gain from the device and people are treated source heat gain fresh air, and moisture.

Always heated in winter, a volume method, the desired temperature is maintained at a constant volume, it aims to set the heat flowing into the outer cold. Heat will flow to the external environment surrounding the lower temperature of the heated volume of the building elements, wherein said heat loss. In summer, a volume flow of heat cooled by air conditioning occurs in the opposite direction. the internal temperature as required by the desired comfort conditions in volume, will always be at a value below the outside temperature, heat gain here would be a question for the volume. Essentially heat gain, comprising not only includes the heat goes outside, a variety of internal heat will be transferred from the source volume.

Heat Gain Account

In principle, the amount of heat in the winter and the heat out of the direction of transition for the summer calculation seems to be exactly the same situation is quite different. The main reason for this difference is not constant that corresponds to winter in permanent regime of heat flow in a sudden summer heat flow is suddenly short period of time in varying amounts. Winter into account will be the basis adopted for the area outside air temperature, and we get a temperature change neglected for 24 hours. In this case, the calculation of the temperature difference between the heat flow will remain constant heat flow occurs at steady state. Write the outside temperature and the radiation temperature of the sunlight in different phases carry both 24-hour day during periods show a periodic change. A succession of these room temperature also occurs at different times during the day.

Cooling load are many factors that influence the calculation and determination of these forces are often precisely because they are affiliated with each other in a complex manner. For this reason, it requires very careful analysis. [one]

Heat Gain Calculation

Of air conditioners in the calculation of the load required for the election to be conditioned as the heat generated by the heat sources are in the scene as well, need to be taken into account in the design of the heat entering the space outside day. A design day, the external environment has reached the highest value combination of dry and wet bulb temperature, radiation from the sun, no fog will reduce or less and can be defined as the day when all of the internal load is normal. for the space to be air conditioned, the peak load realized that day and hour, often were detected in an easy way, sometimes a day, you may need to separately account for certain hours.

Total sudden heat gain:

1 heat gain from windows
– Conduction, convection heat from the glass and realized gain
– Solar radiation, the heat gain from windows
2. Exterior walls and heat gain from the roof
3. Interior partitions, ceiling and floor heat gain realized
4. heat gain from people
5. Air conditioning heat gains from sources within the space made
– Lighting
– Miscellaneous appliances (ovens, refrigerators, irons, radios, such as TV)
– Other heat sources (hot fluid passes through pipes, etc.)
6 taken to the outside air ventilation and heat gain from infiltration
7. caused by moisture seeping through building elements
8 can be expressed as heat gain from the channel.

Incoming heat gain through glass

heat gain from solar radiation through glass:

Q = A × (R / A) qg
Here :
A: Image area (m2)
AR / A: radiation transmission rate window (W / m2)
qg: Corrections and shading factor

by conduction and convection of heat gain in the glass:

QK = M × A × (Td – Tu)
Here :
K: total heat transfer coefficient of the window (W / m2K)
A: Image area (m2)
TD: Outdoor temperature (° C)
T: Internal temperature (° C)

Outer Wall and Roof From The Heat Gain

Q = C × × Dt
K: The walls and roof of the total heat transfer coefficient (W / m2K)
A: The heat flow to other areas (m2)
Dt: equivalent temperature difference (° C)

Interior partitions, ceilings and flooring from incoming Heat Gain

Q = M × A × (TC – T)
Here :
K: Air-conditioning made the scene, the total heat transfer coefficient of neighboring locality separating structural elements (W / m2K)
A: The ceiling and the floor area (m2)
Td: Neighbour volume temperature (° C)
T: Internal temperature (° C)

From The People Heat Gain

People temperature of their environment, according to state their clothes, and their activities gives heat to space.
Q = Qd + Fs
Qd = Qd × n × n × Qg = Qg
Here :
n: Number of people (W)
Qd: sensible heat gain value per capita (W)
Fs: latent heat gain value per capita (W)

Air conditioning made Mahal contents from various sources Heat Gain

Qayd = k1 × k2 × QTE
QTE: Light power (W)
K2: Special fixtures factor (for incandescent lamp 1, 1.2 for fluorescent lamps)
k1: Using factor (the luminosity of Sattar account where the maximum load is the ratio of total lighting power.

Qmot R = k1 × × k2 is nmot
Nmot is: Motor power (W)
k1: Using factor (maximum load time is mainly taken into account during the motor as a percentage of the money during the average working.
K2: Load factor (captured power during peak load hours taken into account essentially, is the ratio of power indicated on the label.)

The hot fluid in the pipes:
= Qbor × Lbor of the Qbor
qbor of: heat pipes, which gain value per meter (W / m)
Lbor of: Pipe length (m)

Received for incoming ventilation air and from external infiltration Heat Gain

Heat gain value from the outside air for ventilation taken:
VD qd = ρh × × × BF CPH × (Td-Tu) / 3600 W
Fs = VD ρh × × × BF × HSB (Wd-WI) / 3600 W

Here :
ρh: air density of 1.2 kg / m3
VD: the amount of outside air for ventilation taken (m3 / h)
BF: Coil of the by-pass factor (0.05, 0.2)
CPH: moist air specific heat (kJ / UPS)
HSB: latent heat of evaporation at room temperature (kJ / kg)
TD: Outside temperature (° C)
Ti: Indoor air temperature (° C)
WD: External specific humidity of the air (kg water vapor / kg dry air)
WI: The specific humidity of the interior air (kg water vapor / kg dry air)

Because of the air entering the space inside the infiltration heat gain through:
Ρh qd = V × × × BF CPH × (Td-Tu) / 3600 W
Fs = V × BF ρh × × × HSB (Wd-WI) / 3600 W
Vi = Σ (al) × R × H × Z

Here :
VI: Enfitrasyo with the amount of incoming air (m3 / h)
A: permeability of the doors and windows (m3 / hm)
L: circumference of the opening portions of doors and windows (m)
R: Mahal characteristics
H: Structure characteristics
Z: time factor for corner rooms

Derived from leaking moisture from building elements Heat Gain

Fs = × n × AW
Here :
A: Area (m2)
n latent heat carrying value of wall materials (W / m2 AW)
.delta.w: Internal and external air specific humidity difference (kg steam / kg dry air)

With the Channel Heat Gain

From places that would be conditioned on the channel.
Q = ρh VH × × × L × CPH ΔTK
VH: the amount of air in the channel (m3 / h)
ΔTK: temperature rise in the air channel (° C)
L: the climatized spaces the channel length (m)


Q = k × × Dt
k: Channel the heat transfer coefficient (W / m2K)
A: heat transfer area of the channel (m2)
Dt: temperature difference between the ambient air inside the duct (K)

source heat gains from people and devices that you can use in the calculations;

Derived from People Heat Gain
From The People Heat Gain

Heat Gain Resulting From Device
Heat gain from devices

A comparison chart of different quarters to check the accounts that you have done;

Comparison Chart
Comparison Table Air Conditioning and Heat Gain

Heat Gain Calculation Programs
Explanation Download Link
1. Heat Gain Calculation.xls Heat Gain Account Download
2- Cooling load Calculation.xls Cooling Load Calculation Download
3. Practical cooling load Calculation.xls Practical cooling load Download
4- Heat Gain Calculation.xls Heat Gain Account Download
5. Cooling Calculation.xls Cooling Account Download
6 Practical Air Calculation.xls Practical Air Conditioning Account Download
7- cooling load Calculation.xlsx Cooling Load Calculation Download
COOLPAC Heat Gain Calculation Scheme (English) > COOLPAC Heat Gain Download
Bamaload Heat Gain Calculation Scheme (English) Bamaload Heat Gain Download
Online Alarko Carrier Air Conditioner Selection Online Alarko Carrier Air Conditioner Selection Online Calculations
MTH – must be purchased. MTH MTH
Trane HVAC Design Software – Demo is to be purchased. Trane HVAC Design Trane Demo
Carrier Hap (Hourly Analyser Program) – must be purchased. > Carrier Pill TTMD
Fine Hvac – must be purchased. > Fine Hvacr Fine Hvac

Source: Air Conditioning and Ventilation, Şadi TAMER

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