Development of a Thermal Environment Analysis Method for a Dwelling Containing a Colonnade Space through Coupled Energy Simulation and Computational Fluid Dynamics
Abstract
:1. Introduction
2. Theoretical Background to the Proposed Method
2.1. Difference in Simulation Calculations Using Various Heat Flow Paths
2.2. Proposed Method
2.3. Proposed Calculation Method
3. Simulation Measurement and Analysis Conditions
3.1. Outline of Target Laboratory Housing and Measurement Points
3.2. Outline of Actual Measurement Process
3.3. Analysis Model and Calculation Conditions
4. Verification of the Accuracy of the Proposed Method
4.1. Procedure for Verifying Accuracy of the Proposed Method
4.2. Estimation of Unknowns Using THERB
4.3. Confirmation of CFD Accuracy Using Measured Values
4.4. Calculation of Distribution Coefficient
4.5. Accuracy Verification of Distribution Coefficient
4.6. Sensitivity Analysis by Air Inlet Angle
4.7. Confirmation of Heat Source Addition
- (1)
- The heat transfer coefficient was calculated for each floor.
- (2)
- The amount of input heat of the temporary air conditioner was distributed using the coefficient of thermal diffusion
- (3)
- The heat input was added to each zone calculated for each floor and added as the net heat input
- (4)
- The convergence calculation was performed for heat input
- (5)
- Accuracy verification was conducted for the main rooms
5. Conclusions
- (1)
- The boundary conditions (surface temperature and air conditioner flow velocity) for CFD were calculated using THERB, and it was confirmed that the calculated surface temperature was almost identical to the measured value. Additionally, we calculated the momentary amount of heat input and confirmed that the air conditioning set temperature was reached with only a small amount of heat input (approximately 1300 W) because the insulation performance was very good.
- (2)
- The coefficient of thermal diffusion was calculated using CFD from physical quantities such as heat loss through the walls and the temperature of each zone. It was confirmed that the temperature of the main living room could be accurately predicted. The heat input was compared with the accuracy of the coefficient of thermal diffusion.
- (3)
- Sensitivity analysis was conducted to investigate the influence of the air inlet angle on the room temperature. When the air inlet angle was 30°, little difference existed between the actual measured value of the air outlet temperature and the measured value, and it was also confirmed that the amount of input heat was appropriate to apply as a measurement condition. It was confirmed that the air outlet temperature tended to increase as the air inlet angle in the horizontal direction increased. It was confirmed that the coefficient of thermal diffusion demonstrated little fluctuation due to the air inlet angle and was within the range of approximately ±0.5 °C as a temperature range.
- (4)
- The convergence calculation was performed by calculating the coefficient of thermal diffusion when the heat quantity calculated using THERB was input to the air conditioner of each floor to confirm that the heat sources could be added. The method of distributing the heat load was verified. By performing a convergence calculation for the purpose of calculating the heat load of each floor using ES, it was found that the room temperature of the main living room demonstrated an average error of approximately 0.3 °C.
Author Contributions
Funding
Conflicts of Interest
Nomenclature
Coefficient of thermal diffusion [–] | |
Specific heat of air [J/kg·K] | |
specific gravity [kg/m3] | |
iZone volume [m3] | |
iZone temperature [K] | |
iZone reference temperature [K] | |
Heat loss from the wall [W] | |
Amount of input heat of air conditioner [W] | |
Specific heat of air conditioner inlet air [J/kg·K] | |
Aair | Air outlet area [m2] |
Air outlet temperature [K] | |
Air outlet port air temperature [K] | |
Ti,j | Room i, temperature of target element j [K] |
Apparent volumetric specific heat of rooms containing furniture [J/m3·K] | |
Si,j | Area of room i, target element j [m2] |
hi,j | Convective heat transfer coefficient of room i, target element j [W/m2·K] |
Vo | Ventilation rate with the outside air [m3/s] |
C | Volumetric specific heat of air [J/m3·K] |
qi | i Zone heat load [W] |
v | Air inlet speed [m/s] |
L | Total heat load [W] |
Tair | Outlet temperature [K] |
Ts | Air outlet temperature [K] |
qr | Heat quantity of r floor [W] |
Qr | Sum of heat load of each zone at the time of air-conditioner operation of the r floor distributed by coefficient of thermal diffusion [W] |
qh | Sum of the heat quantity of each zone transported to the h floor when the r floor air conditioner was distributed according to the coefficient of thermal diffusion [W] |
Contribution ratio of indoor climate (CRI) | When multiple heat sources are present, a standard flow field is created and fixed to calculate the thermal contribution to the space per heat source. CRI is a method for predicting the temperature at any point by adding the temperatures at any point together |
Coefficient of thermal diffusion (α) | In energy simulation (ES), thermal diffusion is difficult to calculate, and the effect of strong directional advection is calculated beforehand by computational fluid dynamics (CFD) and is reflected in the non-stationary calculation of ES. The influence of the air conditioning advection on the zone that divides the space arbitrarily can be considered, which is convenient for the ES. |
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Artificial Weather Room Setting | Tokyo Prefecture Fuchu City |
---|---|
Ventilation frequency | 0 times |
Air conditioner model number | 1F:S50FTSP-W (Opening area:0.049 m2) |
2F:S28FTSS-W (Opening area:0.063 m2) | |
Setting | Winter |
Temperature | 20 °C |
Air inlet angle | 30° from the horizontal plane |
Air inlet speed | Strong |
Weather Conditions | Case | Convection Air Conditioner Operation Status | |
---|---|---|---|
1F | 2F | ||
Winter | Case1 | ○ | ○ |
Case2 | ○ |
Item | Conditions |
---|---|
Calculation time interval | 10 minutes interval |
Weather data | Measured value (temperature and humidity) |
Ventilation frequency | 0.2 air changes/h |
Room occupants | None |
Air conditioning set temperature | Measured value |
Heat input during air conditioning | See Figure 8 |
Item | Conditions |
---|---|
Turbulence model | Low Re type k-ε model |
Mesh number | Approximately 3.2 million mesh elements |
Air inlet angle | 30° |
Air inlet temperature | 318.15 K |
Air inlet velocity | 2.4 m/s |
Calculation code | STAR-CCM+11.02.010 |
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Share and Cite
Yamamoto, T.; Ozaki, A.; Lee, M. Development of a Thermal Environment Analysis Method for a Dwelling Containing a Colonnade Space through Coupled Energy Simulation and Computational Fluid Dynamics. Energies 2019, 12, 2560. https://doi.org/10.3390/en12132560
Yamamoto T, Ozaki A, Lee M. Development of a Thermal Environment Analysis Method for a Dwelling Containing a Colonnade Space through Coupled Energy Simulation and Computational Fluid Dynamics. Energies. 2019; 12(13):2560. https://doi.org/10.3390/en12132560
Chicago/Turabian StyleYamamoto, Tatsuhiro, Akihito Ozaki, and Myonghyang Lee. 2019. "Development of a Thermal Environment Analysis Method for a Dwelling Containing a Colonnade Space through Coupled Energy Simulation and Computational Fluid Dynamics" Energies 12, no. 13: 2560. https://doi.org/10.3390/en12132560