Effect Of Heat Removal Research Articles

A new ventilation performance index considering relative changes in environmental parameters: A numerical study

The ventilation index plays a crucial role in evaluating and selecting ventilation systems. However, existing studies focus only on the "effectiveness" of ventilation systems but usually ignore the "extent of the effect" caused by ventilation, and no relevant indexes are available. To address this issue, this study aims to propose a new ventilation index named the equivalent ventilation number (EVN), which considers the relative change in environmental parameters. The application potential of the EVN index was numerically examined in a virtual hospital ward setting with varying air changes per hour (ACH), thermal loads, air distribution patterns, contaminant source intensities, and local air supply rates. The results demonstrate that the highest average temperature-based EVN and CO2-based EVN are obtained when ACH increases from 6 h−1 to 12 h−1 and local supply air velocity increases from 0 m/s to 1 m/s, with values of 0.66 and 1.49 respectively. Furthermore, EVN values differ across different ventilation conditions and locations. The effect of changing ventilation conditions on ventilation performance assessed by heat removal effectiveness and temperature-based EVN, as well as contaminant removal effectiveness and CO2-based EVN, is opposite in 4 out of 10 cases and 3 out of 10 cases, respectively. The average EVN values calculated based on temperature and contaminant changes differ among all cases, with the largest difference of 1.2. The proposed EVN is anticipated to be an effective index for quantifying and comparing the "extent of the effect" caused by ventilation systems under various ventilation conditions.

Geometric-parameter influence and orthogonal evaluation on the thermal environment for an impinging jet ventilation system inlet

Numerical simulations are conducted to illustrate the geometric-parameter influences and orthogonal evaluation of heat removal effectiveness and dimensionless buoyant jet length scale for impinging jet ventilation system, after the full-scale measurements conduced. Two geometric parameters taken into consideration are the airflow inlet length, width and height from floor. Firstly, each geometric-parameter influence is investigated individually among its varying range while maintaining the other geometric parameters. Secondly, an orthogonal analysis is performed for evaluating the importance of each geometric-parameter on the thermal environment and thermal comfort performances.

Experimental Study of Indoor Air Distribution and Thermal Environment in a Ceiling Cooling Room with Mixing Ventilation, Underfloor Air Distribution and Stratum Ventilation

A ceiling cooling system integrated with a mechanical ventilation system has been widely used in modern buildings with large sensible cooling loads due to the high thermal comfort level and large energy efficiency. However, there is a lack of systematic research on the influence factors such as ceiling surface temperature and cooling load on the indoor air distribution and thermal environment, and the impact of ventilation system type in the ceiling cooling room is still unclear. Therefore, this paper presented an experimental study of indoor air distribution and thermal environment in a ceiling cooling (CC) room with mixing ventilation (MV), underfloor air distribution (UFAD) and stratum ventilation (SV); the ceiling surface temperature was 17 °C–26 °C and the internal or external cooling load was 41.5 W/m2–69.5 W/m2. The results showed that the vertical air temperature difference and contaminant removal effectiveness were 0.2 °C–0.4 °C and 0.53–0.85 with CC + MV, 0 °C–1.2 °C and 0.68–1.25 with CC + UFAD and 0.3 °C–0.9 °C and 0.50–0.83 with CC + SV, and the corresponding heat removal effectiveness and air diffusion performance index were 0.96–1.11 and 96–100%, 0.9–1.5 and 57–100% and 1.11–1.34 and 71–100%, respectively. Moreover, the difference between mean radiant temperature and air temperature and the predicted mean vote of thermal sensation were from 0 °C to 0.9 °C and between 0 and 0.26 with CC + MV, from −0.1 °C to 2.2 °C and between −0.1 and 0.42 with CC + UFAD and from −0.1 °C to 0.9 °C and between −0.2 and 0.13 with CC + SV. Hence, the ventilation system type clearly affected the indoor air distribution and thermal environment in the ceiling cooling room, and the experimental results would be beneficial for the design and control of a ceiling cooling system combined with a mechanical ventilation system in practice.

Sensitivity analysis of indoor air distribution performances in an office room with ceiling cooling and mechanical ventilation

A hybrid system with a ceiling cooling (CC) system and a mechanical ventilation system has been extensively applied in modern office buildings with large sensible cooling loads. Both the chilled ceiling and supply air may greatly influence indoor air distribution in the office room. Therefore in this paper, indoor air distribution performances in a ceiling cooling room with underfloor air distribution (UFAD) or mixing ventilation (MV) were sensitively analyzed by numerical simulation. Indoor air distribution performances, which were evaluated by the heat removal effectiveness, contamination removal effectiveness and air diffusion performance index, were quantitatively analyzed by using the orthogonal experiment method. The results showed that when the supply air temperature was 18 °C-24 °C for CC + UFAD and 16 °C-21 °C for CC + MV, the heat removal effectiveness changed by 0.01 with 1 °C increment of supply air temperature or ceiling surface temperature, and the contamination removal effectiveness increased by 0.001-0.002 with 1 W/m2 increment of external sensible cooling load. Moreover, the air diffusion performance index increased by 0.6%-1.1% with 1 °C increment of supply air temperature, and it decreased by 0.02% with 1 W/m2 increment of internal sensible cooling load. Finally, formulas of heat removal effectiveness, contamination removal effectiveness and air diffusion performance index for CC + UFAD and CC + MV were obtained by fitting, and they may provide guidance for the optimal design and control of a hybrid system with a ceiling cooling system and a mechanical ventilation system.

Effect of active chilled beam layouts on ventilation performance and thermal comfort under variable heat gain conditions

The active chilled beam system has been popularly used in office and meeting rooms. There are very few studies of their terminal configuration on the thermal comfort and ventilation performance of systems with different heat gains. A comparative experimental study was implemented in mock-up office and meeting rooms to provide a comprehensive evaluation of the airflow patterns, air distribution, ventilation effectiveness, and local thermal comfort of the 4-way system. Four different terminal layouts with two types of the chilled beams (600 unit and 1200 unit sized 0.6 m × 0.6 m and 1.2 m × 0.6 m, respectively) were tested at three heat gain levels: low (46W/m2) and medium (66W/m2) heat gains in the office room, and high (92W/m2) heat gain in the meeting room. The results revealed that the terminal layouts and heat gain levels had significant effects on air distribution and local thermal comfort. The increased heat gains generated lower heat removal effectiveness, worse indoor thermal uniformity, and increased risk of draught. Generally, the 1200-unit system performed better than that with 600 units for heat removal effectiveness and contaminant removal effectiveness. In terms of local thermal comfort, the 600-unit system generally provided higher performance than that with the 1200-unit system. The practical recommendations for the system design and operation stages are provided based on the operating range of the 4-way systems under variable terminal layouts and heat gain conditions.

Numerical modeling of filtration gas combustion in a cylindrical radiation burner for contactless heating of materials

• A new configuration of radiant burner is considered. • The study of the effect of heat loss on the stability of the filtration combustion in a porous medium is carried out • Numerical modelling of the combustion inside a burner with axial fuel supply has shown the possibility of stable operation at high temperature levels. • There is a range of pressure drops at which the process of contactless heating of the material to high temperature levels can be carried out. The filtration gas combustion in a porous cylindrical tube with axial injection of combustible mixture is numerically investigated. This configuration can be potentially used as new type of heater for the contactless heating of materials in industrial processes. The material under treatment is placed inside the cylindrical porous tube and is heating by radiative flux from the cylindrical tube wall. The simulation of the filtration gas combustion in porous burner was carried out within the framework of the two-temperature thermal-diffusion model. Conducted numerical modeling yields qualitative description of the effects of heat removal from the burner on the limits of a stable combustion regime. The data about range of the gas flow rates and the intensity of the heat losses on the burner's inner surface corresponding to the stable combustion were obtained. The temperature distributions in the gas and the porous burner were as well gas flow field were obtained in general case, without addresing to the details of the material processing.

Research on decay heat removal effectiveness in pool-type fast reactor CEFR based on system code SAC-DRACS coupled with CFD software

In station blackout(SBO) accident, the establishment and maintenance of natural circulation in the China Experimental Fast Reactor(CEFR) mainly relies on the decay heat removal system(DHRS). However, due to the complex structure of the reactor, it’s very difficult to model the full-scale CEFR. In the present work, DHRS and the primary circuit system of the CEFR are modeled by the System Analysis Code for Direct Reactor Auxiliary Cooling System (SAC-DRACS) code and three-dimensional CFD software FLUENT, respectively. Then the long-term transient simulation of 4000 s is calculated by coupling SAC-DRACS and CFD codes. The overall temperature stratification and local core temperature variations in the pool caused by DHRS are analyzed. Meanwhile, the residual heat removal capacity of DHRS is evaluated, the average core outlet temperature does not exceed 500.3 °C under the action of DHRS. This work provides an extension of the research method for the pool-type fast reactor safety analysis.

A Numerical and Experimental Investigation of a Confluent Jets Ventilation Supply Device in a Conference Room

In this study, confluent jets ventilation (CJV) supply devices with three different nozzle arrays (1 × 19, 2 × 19, 3 × 19) were investigated both numerically and experimentally at two different airflow and supply air temperature set-ups. The performance of the CJV supply devices was investigated concerning thermal comfort, indoor air quality (IAQ), and heat removal effectiveness in a conference room environment. A comparison between the experimental and numerical results showed that the ϑ2¯−f model had the best agreement out of the investigated turbulence models. The numerical results showed that the size of the array had a great impact both on near-field development and on the conditions in the occupied zone. A larger array with multiple rows and a lower momentum conserved the inlet temperature and the mean age of the air better than a single-row array with a higher momentum. A larger array with multiple rows had a higher IAQ and a greater heat removal effectiveness in the occupied zone because the larger array conserved the mean age of air better and the buoyancy driven flow was slightly better at removing the heat. Because of the lower inlet velocities, they also had lower velocities at ankle level, which decreased the risk of draft and thermal discomfort.

Energy performance index of air distribution: Thermal utilization effectiveness

The energy performance index is crucial for the energy-efficient design and operation of air distribution. Heat Removal Efficiency (HRE) is a widely used energy performance index, and Energy Utilization Coefficient (EUC) and Effectiveness of Heat Removal (EHR) are alternatives to HRE. This study justifies that these existing indices are unreasonable and incompetent as energy performance indices. This study also proposes a new index called Thermal Utilization Effectiveness (TUE) and verifies its efficacy as an energy performance index via theoretical analyses and experiments on stratum ventilation, displacement ventilation, and underfloor air distribution. EUC is not a suitable energy performance index since it does not consider the relative contributions of the occupied and unoccupied zones to the energy performance of air distribution. EHR cannot qualitatively distinguish the energy performance of air distribution because of its floating benchmark point. HRE cannot quantitatively distinguish the energy performance of air distribution because it unequally weighs the thermal energy of the air temperature of the occupied zone. TUE accounts for the relative contributions of the occupied and unoccupied zones to the energy performance with the help of the exit air temperature, qualitatively distinguishes the energy performance because of its two fixed benchmark points, and quantitatively distinguishes the energy performance by equally weighing the thermal energy of the air temperature of the occupied zone. Therefore, TUE overcomes the drawbacks of EUC, EHR, and HRE, and is a reasonable and competent energy performance index of air distribution.

Occlusion of the vein adjacent to colorectal cancer liver metastasis as a way to increase the radicality of percutaneous radiofrequency thermal ablation

Objective.To evaluate the effectiveness of preoperative coagulation of the vein adjacent to a tumor nodule in sonographically-guided percutaneous radiofrequency thermal ablation of perivascular liver metastases of colorectal cancer.Materials and methods.To address the issue, we compared the results of sonographically-guided percutaneous radiofrequency thermal ablation of perivascular liver metastases of colorectal cancer in 27 patients (aged 60.5 (58; 68) years) without prior coagulation of the adjacent vein (control group) and 26 patients (62.0 (60; 74)) with prior coagulation of the adjacent vein (experimental group).Results.Lower incidence of residual tumor in the ablation area in the patients with prior coagulation of the adjacent vein (14.3 % vs. 29 % of the patients in the control group) and a higher relapse-free survival of such patients (65.2 % vs. 53.6 % and 55.6 % vs. 33.3 %) were reported as compared to the group without prior coagulation of the adjacent vein (after 6 and 12 months, respectively).Conclusion.Preoperative coagulation of the vein adjacent to colorectal cancer liver metastasis allows reducing the effect of heat removal from the RFA zone, thereby contributing to higher radicality of the treatment and resulting both in a lower incidence of residual tumor in the ablation zone and a higher relapse-free survivalof patients, notably without signifcant concomitant changes in the affected part of the liver (segment atrophy).

Numerical investigation on mechanisms and performance of column attachment ventilation for winter heating

Column attached ventilation (CAV) is a new form of air distribution based on pillars widely distributed in buildings. Due to thermal buoyancy in the room, the airflow mechanism and performance of CAV is uncertain when it is applied for winter heating, especially in buildings with large space. In this study, a simplified three-dimensional model was established based on a shopping mall. A Computational Fluid Dynamics (CFD) method was employed to simulate the airflow in the room. Archimedes number (Ar) was used to study air distribution and ventilation performance. Results indicated that CAV could be used for room heating, and inertia force was the main driving force of the airflow. In the occupied zone, air velocity and temperature could be controlled by supply air velocity and temperature. Ar was related to air distribution and ventilation effect. In selected cases, Ar less than 2.241 × 10−3 was the prerequisite for effective air distribution. Heat removal effectiveness was linearly related to Ar, and it increased by about 0.01 when Ar reduced by 0.1. CAV saved more energy than mixing ventilation to achieve the same parameters of the occupied zone. These results provide a theoretical basis for the application of CAV in winter conditions.

The Effect of Heat Removal during Thermophilic Phase on Energetic Aspects of Biowaste Composting Process

Composting is the natural, exothermic process where the huge amount of heat that is created is an issue of organic matter decomposition. However, too high temperature can reduce the microbial activity during the thermophilic composting phase. The aim of this study was to analyze the effect of heat excess removal from composted materials on the process dynamic. The experiment was performed in two parallel bioreactors. One of them was equipped with a heat removal system from the bed of the composted material. Three experiments were carried out with mixtures of different proportions: biological waste, wheat straw, and spent coffee grounds. The content of each option was determined based on a previous study of substrates to maintain the C/N ratio for the right composting process, provide adequate porosity composted material, and enable a proper degree of aeration. The study showed the possibility of receiving part of the heat from the bed of composted material during the thermophilic phase of the process without harm both to the course of composting and the quality of the final product. This shows that at a real scale, it can be possible to recover an important amount of heat from composted materials as a low-temperature heat source.

A Comparative Study of Performance Between Two Combined Ventilation Systems and Their Effect On Indoor Air Quality and Thermal Comfort Inside Office Rooms

The most important problems that must be solved and improved in ventilation research are indoor air quality and thermal comfort. The Iraqi climate is characterized by being very hot and dry, so fresh cold air must be provided to the occupants of offices, factories, workshops and others to improve thermal comfort and increase their efficiency. This study focused on improving the quality of inhaled air by using two types of ventilation systems (mixing and displacement ventilation) in combined with a personal ventilation system. This study was a set of numerical tests that were conducted to predict the temperature distribution, air movement and speed inside a closed office room subject to the Iraqi climate in terms of weather conditions. This numerical study was carried out using (AIRPAK3.0.16) which is used to solve turbulence equations, Naiver stock, energy equations, and use of (FVM). A thermally isolated room was simulated with a personal ventilation system that supplies air at temperatures from 21 to 23 °C for case I (personal and mixing) and supplies air at a temperature from 18 to 20 °C for case II (personal and displacement) the air velocity for both cases was 0.6 m/s. It was found that there was a positive effect of the personal ventilation system in both cases, but its effect was more pronounced in the first case, through numerical calculations for each of the effectiveness of heat removal (εt) and air distribution performance index (ADPI), where (74.361) and (1.549) were found for the first case, and (68.321) and (1.71) for the second case.

Impact of impinging jet ventilation on thermal comfort and indoor air quality in office buildings

This paper is dedicated to research of impinging jet (IJV) air distribution method. This system provides the desired indoor climate in office buildings. This paper describes the experimental requirements and boundary conditions for the CFD simulation and experiment in the climate chamber. The necessary modelling scenarios were developed to review the operation of the ventilation system according to different climatic conditions (winter, summer), human positions in the room and the shape of the supply duct. It is concluded that the shape of the air opening has little effect on the contaminant and heat removal effectiveness, 114%–122% and 1.12–1.16 respectively. At the same time, there is a large impact on the air exchange effectiveness (0.74–0.91). It was experimentally noted that in terms of contaminant removal and air exchange effectiveness, the circular opening provides better results. The human position depends on the supply temperature and flow velocity. By analyzing different scenarios, it was determined that the minimum acceptable distance to maintain thermal comfort within the standard requirements from the supply outlet is 1.7 m. As the distance from the air opening increases, the vertical air temperature difference at the height of 0.1–1.1 m decreases more than 2 times – from 1.9 K/m to 0.7 K/m. It is concluded that impinging jet ventilation has a great potential for use in office spaces both in winter and summer scenarios. This system significantly improves thermal comfort and indoor air quality. Applying impinging jet ventilation (IJV), limitations and peculiarities of the system such as supply air velocity, temperature and shape of the air duct must be carefully evaluated.

On the Ventilation Performance of Low Momentum Confluent Jets Supply Device in a Classroom

The performance of three different confluent jets ventilation (CJV) supply devices was evaluated in a classroom environment concerning thermal comfort, indoor air quality (IAQ) and energy efficiency. The CJV supply devices have the acronyms: high-momentum confluent jets (HMCJ), low-momentum confluent jets (LMCJ) and low-momentum confluent jets modified by varying airflow direction (LMCJ-M). A mixing ventilation (MV) slot jet (SJ) supply device was used as a benchmark. Comparisons were made with identical set-up conditions in five cases with different supply temperatures (TS) (16–18 °C), airflow rates (2.2–6.3 ACH) and heat loads (17–47 W/m2). Performances were evaluated based on DR (draft rating), PMV (predicted mean vote), ACE (air change effectiveness) and heat removal effectiveness (HRE). The results show that CJV had higher HRE and IAQ than MV and LMCJ/LMCJ-M had higher ACE than HMCJ. The main effects of lower Ts were higher velocities, DR (HMCJ particularly) and HRE in the occupied zone as well as lower temperatures and PMV-values. HMCJ and LMCJ produce MV conditions at lower airflow rates (<4.2 ACH) and non-uniform conditions at higher airflow rates. LMCJ-M had 7% higher HRE than the other CJV supply devices and produced non-uniform conditions at lower airflow rates (<3.3 ACH). The non-uniform conditions resulted in LMCJ-M having the highest energy efficiency of all devices.

An experimental and numerical investigation into scaling considerations for moderator circulation experiments

The moderator system in a CANDU reactor provides the unique ability to provide emergency cooling to the fuel in postulated severe accidents during the early phases of the transient. A key criteria which dictates the effectiveness of heat removal during these events is the integrity of the fuel channel assembly. This in turn relies on the prevention of dryout on the calandria tube. The main tool used to demonstrate adequate margins to dryout on the calandria tubes is Computational Fluid Dynamics (CFD). While several experimental datasets are available for validation of these tools, the historical facilities lack the specific geometrical features present in some of the older CANDU designs. The historic tests were typically scaled based on the so-called Archimedes number and non-dimensional heat flux. To extend the validation database two unique 1/16th scale (based on vessel diameter) experiments are performed which include features found in the moderator systems of two operating CANDU designs. The primary goal of these new experiments was to generate thermalhydraulic data for validation of CFD codes, but several additional tests were performed to examine the potential impact of scaling on the results. This paper demonstrates a consistent conservative bias in the CFD predictions with respect to maximum temperature in the experiments over the range of conditions tested. The combination of CFD and experimental observations concludes that the likely cause of the bias is due to CFD’s over prediction of inlet jet dissipation leading to less cold fluid penetration in the heated core of the test section. In terms of scaling, a combination of experimental evidence and supporting CFD simulations indicate that the historical scaling parameters do provide some level of qualitative similarity in the mixed-convection regimes in the vessel, but some revision to account for geometrical and flow pattern deviations may be necessary.

A numerical study on the effect of column layout on air distribution and performance of column attachment ventilation

Based on the structural characteristics of existing buildings and the disadvantages of current mixed ventilation mode in the application to large space buildings, an original column attachment ventilation (CAV) has been proposed. In this study, the experiment utilized a room space with four columns uniformly distributed in the space to visualize the movement of attached airflow along the cylinder surface and the floor, the numerical technique was employed to study the effects of the column layout (i.e., uniform, centralized, dispersed, and crossed distribution) on the air distribution of CAV mode in a standard four-column full scale model of a shopping mall. Seven indices, including airflow pattern, air diffusion performance index (ADPI), air temperature distribution, heat removal effectiveness, draught rate (DR), predicted mean vote (PMV), and carbon dioxide (CO2) concentration, were used to assess the ventilation performance. In the CAV mode with a uniform column layout scheme, the experimental results indicated that the air supply flows downward along the wall surface, forming a secondary attachment with the ground and spreading along the floor in a fan radiation flow mode. Further, an “air lake”—like speed and temperature distribution similar to displacement ventilation (DV) was formed in the occupied zone. In all simulation cases, it was found that the average air velocity was less than 0.25 m/s in occupied zone, the effectiveness for heat removal was more significant than 1.0, DR value was less than 20%, the PMV level can also satisfy most people. The average CO2 concentration was around 470 ppm in the occupied breathing zone. These results indicated that the CAV mode could be an efficient air distribution method. They demonstrated the technical feasibility of applying the CAV in the space under different column layout schemes.

Experimental Evaluation of the Ventilation Effectiveness of Corner Stratum Ventilation in an Office Environment

An experimental study was conducted in a room resembling an office in a laboratory environment. The study involved investigating the ability of corner-placed stratum ventilation in order to evaluate the ventilation’s effectiveness and local thermal comfort. At fixed positions, the air temperature, air velocity, turbulence intensity, and tracer gas decay measurements were carried out. The results show that corner-placed stratum ventilation behaves very similar to a mixing ventilation system when considering air change effectiveness. The performance of the system was better at lower supply air flow rates for heat removal effectiveness. For the heating cases, the draught rates were all very low, with the maximum measured value of 12%. However, for the cooling cases, the maximum draught rate was 20% and occurred at ankle level in the middle of the room.

Impact of chilled ceiling in a high sensible cooling load room with underfloor air distribution

The use of an underfloor air distribution (UFAD) system integrated with a chilled ceiling (CC) cooling system can provide a potentially advanced heating, ventilation, and air conditioning (HVAC) system with high sensible cooling loads in modern office buildings. In this paper, an experimental study of the impact of CC in a room with a high sensible cooling load with UFAD was performed when the chilled ceiling surface temperature increased from 17.0 to 26.0 °C. The vertical distributions of indoor air temperature, air velocity, and pollutant (CO2) concentration were measured and evaluated by the vertical air temperature difference (VATD), turbulence intensity (TI), and contaminant removal effectiveness (CRE), respectively. The results showed that the average VATD, TI, and CRE were 0.1–0.9 °C, 4–40%, and 0.85–1.19, respectively, when the internal and external sensible cooling loads equal 41.5W/m2. These evaluation indices varied clearly when the internal sensible cooling load increased from 41.5 to 69.5W/m2, whereas they were almost the same when the external sensible cooling load increased from 41.5 to 69.5W/m2. The minimum CRE and air diffusion performance index (ADPI) coincided with the maximum heat removal effectiveness (HRE) under a constant cooling load condition. The results suggest that it is better to balance the energy consumption as well as indoor air quality and thermal comfort in a room with UFAD + CC.

Indoor air distribution in a room with underfloor air distribution and chilled ceiling: Effect of ceiling surface temperature and supply air velocity

An underfloor air distribution (UFAD) system integrated with a chilled ceiling (CC) cooling system may be a potential advanced heating, ventilation and air conditioning system in modern non-residential buildings with high sensible cooling loads. This article presents an experimental study concerning the effect of ceiling surface temperature and supply air velocity on the indoor air distribution in a room with UFAD as the internal and external sensible cooling loads change. The vertical distributions of indoor air temperature, air velocity and contaminant (CO2) concentration were evaluated by vertical air temperature difference (VATD), turbulence intensity (TI) and contaminant removal effectiveness (CRE), respectively. The results showed that the average VATD, TI and CRE levels were 0.5°C–1.0°C, 31%–41% and 0.85–1.06 when both internal and external sensible cooling loads were 41.5 W/m2. These evaluation indices varied clearly when the external sensible cooling load increased from 41.5 W/m2 to 69.5 W/m2, whereas they remained almost the same when the internal sensible cooling load increased from 41.5 W/m2 to 69.5 W/m2. The maximum TI coincided with the minimum CRE under the condition of a constant sensible cooling load. Moreover, an air diffusion performance index clearly reduced with an increase in the heat removal effectiveness. It is recommended that it is important to balance the indoor air quality and energy consumption in a room with UFAD + CC.