Fresh Air System Research Articles

A Data Mining-Based Method to Disclose Usage Behavior Patterns of Fresh Air Systems in Beijing Dwellings during the Heating Season

As the popularity of fresh air systems (FAS) in residential buildings increases, exploring the behavioral characteristics of their use can help to provide a comprehensive understanding of the potential for demand flexibility in residential buildings. However, few studies in the past have focused on the personalized usage behavior of FAS. To fill this gap, this study proposes a method based on data mining techniques to reveal the behavioral patterns of FAS usage and the motivations behind them, including motivational patterns, operation duration patterns, and human–machine interaction patterns, for 13 households in Beijing. The simultaneously obtained behavioral patterns, in turn, form the basis of association rules, which can classify FAS usage behavior into two typical residential user profiles containing user behavioral characteristics. This study can not only provide more accurate assumptions and inputs for behavioral stochastic models but also provide data support for the development and optimization of demand response strategies.

Improving indoor air quality and cooling efficiency: Indirect dew-point evaporative cooling in South China summers

The escalating impact of global warming and the increase in respiratory illnesses have heightened the demand for fresh air systems. However, the substantial power consumption and environmental harm associated with traditional air conditioning systems conflict with current international aspirations for carbon neutrality. To address these issues, a high-performance and compact counterflow indirect dew-point evaporative cooler have developed. This innovative design eliminates the U-turn of the working air seen in conventional M-cycle coolers, resulting in reduced pressure drop and enhanced energy efficiency. This study evaluates the performance of the newly developed dew-point cooler and explores its potential use in providing cool and fresh air for indoor spaces during the sub-tropical summer season in Zhenjiang city, Jiangsu province, China. The results indicate that despite the relatively low fan efficiency (ranging from 5% to 36%), a high cooling coefficient of performance (COP) between 5.2 and 9.3 was achieved. The cooler has demonstrated its effectiveness in improving both thermal comfort and air quality indoors. In Zhenjiang, the cooler can function as a standalone cooling device in June. However, during the hotter months of July and August, it is more suitable as an efficient pre-cooling device when used in conjunction with a conventional air conditioner. The developed cooler exhibited highly stable performance over a three-month test period, consistently maintaining effective cooling and fresh air supply. This study confirms the potential of the counterflow indirect dew-point evaporative cooler as a sustainable and efficient solution for improving indoor air ventilation and thermal comfort.

Thermal energy and thermo-economic analysis of PCM-TES for space heating based on low-temperature waste heat: An experimental and numerical study

Great potential for using low-temperature waste heat for energy savings has been revealed in recent years. In this study, a novel PCM-TES unit integrated into a fresh air system was proposed to effectively utilize low-temperature waste heat to address shortcomings of preheating outdoor air for space heating. An experimental setup was built to investigate the heat storage and release performance of proposed unit. Well-validated CFD simulations further parametrically studied PCM thermal characteristics to HTF’s velocity and temperature changes. Energy and thermo-economic analyses were employed to evaluate unit potentials across three Chinese cities with different climate zones. The results showed that charging process was completed in 142–253 min at water temperatures of 55–60 °C; discharging process efficiency increased by 36.10% as the air velocity increased from 2 to 4 m/s. EPI revealed that, theoretically, the system could handle up to 28.2% of the heating demand. Energy and economic analysis indicated the system’s significant potential in colder climates, with Harbin achieving average energy savings of 7.93% and 13.48% over Qingdao and Chongqing, respectively, and cost savings up to 67.65% and 229.61% compared to those cities. This study is expected to shed light on the utilization of low-temperature waste sources for indoor space heating.

Structure design and mechanism research of combined cyclone plate separator based on particle separation

Although there has been much research on the gas–solid separation equipment of cyclone plate, there is still a lot of research space for miniaturization, low resistance, and easy maintenance. In this paper, parallel gas–solid separation equipment is designed based on computational fluid dynamics and experimental verification methods to address the practical problems faced by the fresh air system of the enterprise plant. The internal flow field of the separator is studied by numerical simulation, and the structural parameters of the separator are optimized according to the performance indicators provided by the enterprise. The optimal structure that meets the performance requirements and has the best effect is determined. Subsequently, the actual performance of the optimal structure was verified by wind tunnel experiments, and the deviation between the experimental results and the numerical simulation results was compared. The results show that increasing the number of blades, adjusting the blade angle, and increasing the height of the outer cylinder are beneficial in improving the internal flow field of the separator. Among them, the blade angle significantly affects the tangential velocity and axial velocity of the separator. When these three parameters are increased, the filtration efficiency increases first and then decreases. Finally, when the number of blades is 8, the blade angle is 50°, and the height of the outer cylinder is 0.63 m, the separation efficiency is the highest, and the pressure drop is the lowest. This structure satisfies all performance indicators. The experimental results show that the minimum filtration efficiency is 92.4%, and the maximum pressure drop does not exceed 500 Pa. Compared with the numerical simulation results, the experimental value is 0.29% lower, which shows that the structure has good separation performance and has a significant reference value for the fresh air system of the industrial workshop.

Method of Calculating Outdoor PM2.5 Concentration in Fresh Air Systems Based on Population Density Distribution Regions

With the gradual increase in population density, population migration poses unprecedented challenges to urban environments and their capacity. The fresh air system effectively ensures fresh air in indoor environments. An important parameter affecting the selection of a fresh air filtration system is calculating particulate matter at a concentration of less than 2.5 μm (PM2.5). The PM2.5 concentration values of 31 cities in China from 2017 to 2020 were selected for analysis in this study. Based on mathematical induction and population density zoning, a new method that combines population density zoning is proposed, and the recommended constant K values for different regions are analyzed. The definition of K refers to the ratio of the outdoor design concentration value of PM2.5 to the annual average at different guarantee rates. The air filters for fresh air systems in five typical cities (Harbin, Beijing, Urumqi, Xi’an, Guangzhou) are also used as examples. The K values and selection differences under different recommendation methods are compared and analyzed. Under population migration and urbanization scenarios, the results indicate that the recommended K of the seven major regions method was optimal. Under these conditions, the recommended K values for five typical cities under strict and normal conditions differ from their average K values by 0.07 and 0.04, respectively. This method can accurately select fresh air filtration systems under different population densities; however, population density is related to factors such as policies and the economy and must be updated and revised regularly. On the whole, it provides reference values for the selection of PM2.5 design concentrations in fresh air systems under population distribution differentiation.

Optimal operation strategy predictive control for an integrated radiant cooling with fresh air system based on machine learning

Radiant cooling systems are widely valued for their great comfort and energy-saving potential. However, they still face the risk of condensation in the early stages of operation, especially in case of random occupancy and intermittent operation. This study aims to avoid unacceptable discomfort durations in randomly occupied rooms that installed integrated radiant cooling and fresh air system while consuming as little energy as possible. This paper firstly compares the effects of adopting only the setback or standby cooling strategy in a randomly occupied conference room by simulation. The simulation results demonstrate the necessity for predicting optimal operation strategy. Subsequently, optimal operation strategy predictive models were built using three machine learning algorithms on three datasets. The evaluation results of the models indicate the feasibility of using data from neighbouring cities to improve the generalisation ability of the target city model. Finally, the best one of models was used to predict optimal operation strategy and achieved good results: discomfort durations of 97.56% of the conferences were within the acceptable range. Additionally, compared to only adopting the standby cooling strategy, the radiant cooling system operating time was reduced by 8.88%, and the total energy consumption was reduced by 28.85 kWh. In this study, a model to predict optimal operation strategy is proposed. By simulating and analysing from both comfort and energy perspectives, the optimal operation strategy predictive control method effectively limits the discomfort duration and reduces energy consumption and radiant system runtime. This study provides an example of practical engineering and machine learning applications for radiant cooling systems.

Intelligent generation method of infection risk map and management system in hospital waiting room for respiratory infectious diseases

Respiratory infectious diseases, such as seasonal influenza, pose significant risks to public health safety through airborne transmission. This study aims to explore methods for controlling airborne infection risk in waiting rooms, a hotspot for cross-infection. A database of 990 samples was established by integrating the results of computational fluid dynamics and social force model simulations into the Wells-Riley equation. We introduced two indicators, Pr (Particle Removal Efficiency) and Hr (High-risk Area Ratio), to evaluate the cleanliness performance of waiting room spaces. Additionally, the Sci (Space Cleanliness Index) was proposed as a criterion for evaluating architectural designs and fine-tuning fresh air system operational parameters. We also unveiled the mapping relationship between spatial morphology parameters and ventilation design parameters in relation to the cleanliness performance of waiting rooms. An infection-risk prediction proxy model was established based on machine learning methods, suitable for rapid prediction of spatial infection risks in waiting rooms and optimization of fresh air system operational parameters. The findings can be applied to the selection of hospital design schemes and the optimization of ventilation operational control strategies, aiding in strengthening infectious disease control and reducing the public health safety risks of cross-infection from respiratory infections during peak seasons in hospitals.

Design method for multi-stage fresh air treatment system with high seasonal energy efficiency

Compared to traditional air conditioning systems that only use high-grade chilled/hot water, multi-stage air treatment (MAT) systems use lower grade chilled/hot water and achieve higher energy efficiency. However, the area of heat exchangers in the existing MAT system is designed based on the maximum value of all working conditions, which is large and not appropriate for partial load conditions. Therefore, this study proposes a method for MAT system design wherein the area of heat exchangers can be appropriate for different working conditions. In this study, optimal area ranges for various working conditions in a fresh air system are calculated, and the overlapping range of these optimal area ranges for all working conditions is determined. Then, the performance of the proposed MAT system is numerically calculated, and six different climate zones are selected to evaluate the applicability of the proposed design methods. The results show that: (1) when the system electric power fluctuates within a small range of 3%, the designed area of heat exchangers can vary over a large range of approximately 50% to 150%; (2) compared to the existing MAT system, the designed area of heat exchangers in the proposed MAT system is reduced by 50.0%, and the maximum energy saving rates in the cooling and heating seasons are 10.9% and 9.8%, respectively; (3) in the selected six climate zones, the duration ratio of working conditions where the designed area is not within the optimal range is less than 5%, indicating good applicability of the proposed design method.

Analysis and modeling of fresh air systems usage behavior in residential buildings in Beijing during heating season

Abstract Fresh air systems (FAS) represent an excellent solution for improving indoor air quality. Because FAS has a significant impact on buildings’ energy consumption, it is vital to investigate FAS usage behavior. At present, there is a research gap with respect to individualized FAS usage behavior and prediction models for residential buildings. From November 15th, 2018 to March 15th, 2019, this paper conducted a field measurement and modeling study of FAS usage behavior in thirteen Beijing households. During heating season, the FAS is used intermittently, with an average daily opening duration of 17.5 hours. Based on the “average daily opening duration”, two FAS usage behaviors were identified: economical households and conventional households. The average daily indoor particles matter 2.5 (PM2.5) concentration was observed to be lower in FAS-using households (16.19 μg/m3, 12.30 μg/m3) than in non-FAS-using households (46.1 μg/m3). Outdoor PM2.5 concentration is a motivating factor for FAS opening. The paper used binary logistic regression to predict the FAS status of both economical and conventional households (two classified models), as well as for all tested households (unclassified model). These results suggest that classified models (84.1%, 83.5%) have greater accuracy than the unclassified model (75.9%), opening the possibility of using the average daily opening duration to classify and examine FAS usage behavior. The study provides accurate field data for evaluating FAS usage behavior, as well as a reference for further simulating the energy consumption of FAS-using households.

Synergistic Impact on Indoor Air Quality: The Combined Use of Air Conditioners, Air Purifiers, and Fresh Air Systems

As concerns about indoor air quality increase, air purifiers and fresh air systems are increasingly being used in conjunction with air conditioners in office buildings. To study the synergistic effects of multisystem joint operation on indoor air quality, this study used a combination of experimental and simulation methods to study the indoor particulate matter with a diameter of less than 2.5 µm (PM2.5) and carbon dioxide (CO2) concentrations under different operation conditions. The purification time and the PM2.5 concentration distribution under different conditions were compared with the condition in which the purifier was used alone. The results showed that the purification time required for the condition that the air conditioner runs together with the purifier was shortened by 15.2%. When the fresh air system is running together with the purifier, the purification time can be reduced by 30.4%. It was reduced by 32.6% when the three systems were operating at the same time. The PM2.5 concentration distribution under the joint operating condition was much more even than that under the condition in which the purifier was running alone. To analyze the impact on the CO2 distribution, the CO2 distributions under different joint operations were compared. The results show that the fresh air system can effectively dilute CO2 below 1000 ppm in 30 min. The air conditioner and purifier could help to mix the indoor air to provide a much more uniform indoor CO2 distribution.

Effectiveness of natural ventilation through single-sided window opening in air-conditioning rooms

Since many buildings are not equipped with fresh air systems, many people open windows to allow for natural ventilation while the air conditioner is running. However, prolonged window opening may cause unnecessary energy consumption. Additionally, the diverse ways of window opening lead to significant variations in indoor airflow distribution, consequently impacting ventilation efficiency. Therefore, this study used field experiments and computational fluid dynamics (CFD) to determine the air exchange efficiency and air change rate of single-sided natural ventilation in air-conditioning rooms by fitting the decay curves of tracer gas. CFD simulation was performed using the unsteady Reynolds-averaged Navier-Stokes (RANS) model to examine how window openings affect the room’s air distribution, and the computed indoor CO2 concentration was compared to the corresponding field experiment data. The results show that natural ventilation through the window opening induced constant heat and mass exchange between indoor and outdoor air, which caused extra cooling losses but was globally effective in eliminating indoor contaminants. The air exchange efficiency is influenced to varying degrees by factors such as the air supply register’s position, window opening percentage, and window opening position. The air supply register’s position exerted the most significant impact at 46.45%. Efficient indoor-outdoor air exchange can be achieved by opening windows intermittently. When the window is opened from one side and the opening percentage is 100%, the indoor environment can be improved by opening the window for about 10 min every 39 min for X-direction air supply and about 7 min every 39 min for Y-direction.

Characteristics and Application Analysis of a Novel Full Fresh Air System Using Only Geothermal Energy for Space Cooling and Dehumidification

To effectively reduce building energy consumption, a novel full fresh air system with a heat source tower (HST) and a borehole heat exchanger (BHE) was proposed for space cooling and dehumidification in this paper. The cooling system only adopts geothermal energy to produce dry and cold fresh air for space cooling and dehumidification through the BHE and HST, which has the advantage of non-condensate water compared to BHE systems integrated with a fan coil or chilled beam. Based on the established mathematical model of the cooling system, this paper analyzed the system characteristics, feasibility, operation strategy, energy performance, and cost-effectiveness of the proposed model in detail. The results show that the mathematical model has less than 10% error in estimating the system performance compared to the practical HST–BHE experimental set up. Under the specific boundary conditions, the cooling and dehumidification capacity of this system increases with the decrease in the air temperature, air moisture content, and inlet water temperature of the HST. The optimal cooling capacity and the system COP can be achieved when the air–water flow ratio is at 4:3. A case study was conducted in a residential building in Shenyang with an area of about 1800 m2. It was found that this system can fully meet the cooling and dehumidification demand in such a residential building. The operation strategy of the cooling system can be optimized by adjusting the air–water flow ratio from 4:3 to 3:2 during the early cooling season (7 June–1 July) and end cooling season (3 August–1 September). As a result, the average COP of the cooling system during the whole cooling season can be improved from 6.1 to 8.7. Compared with the air source heat pump (ASHP) and the ground source heat pump (GSHP) for space cooling, the proposed cooling system can achieve an energy saving rate of 123% and 26%, respectively. Considering that the BHE of the GSHP can be part of the proposed HST–BHE cooling system, the integration of the HST and GHSP for space cooling (and heating) is strongly recommended in actual applications.

Influential factors on the energy efficiency of fresh air systems in nearly zero energy buildings

Ensuring precise control of fresh air volume is crucial for minimizing energy usage in nearly zero energy buildings. Research shows that automatic pressure-independent dampers offer a promising solution for maintaining the desired fresh air volume. However, the energy performance of damper-controlled fresh air systems is influenced by multiple factors that have not been thoroughly investigated. This study focuses on examining the impact of influencing factors on the energy efficiency of fresh air systems. Laboratory experiments and field testing were conducted on a typical fresh air system. Subsequently, based on the experimental data, an energy saving model of the damper-controlled fresh air system was developed and validated. The main influencing factors were comprehensively investigated according to the energy-saving model. Results show that damper resistance is one of the main influencing factors on energy efficiency. Pressure-independent damper with a low resistance ratio of less than 48 % are recommended; When the average PM2.5 concentration increases by 1 µg/m3, the energy saving rate decreases by approximately 0.3 %, indicating that pressure-independent dampers are more suitable for use in regions with cleaner air; In the heating season, the energy saving rate increases by approximately 0.075 % when the dry bulb temperature decreases by 1 °C; In the cooling season, the energy saving rate increases by 1.19 % when the wet bulb temperature rises by 1 °C. This study contributes to the development of sustainable building practices by identifying key factors that influencing the energy usage of damper-controlled fresh air systems and further guiding the selection and utilization of pressure-independent dampers in nearly zero energy buildings.

Performance study of a heat pump fresh air unit based on desiccant coated heat exchangers under different operation strategies

Fresh air system is getting more and more important nowadays. The heat pump fresh air system based on the desiccant coated heat exchanger (DCHE) that can handle the latent and sensible load of fresh air efficiently has a large energy saving potential. To improve the performance of the heat pump fresh air system based on DCHE, in this paper, a control system based on PLC is established and the operation strategies of the system are investigated. An operation strategy including automatic control of the opening of the electronic expansion valve based on the suction superheat of the compressor, control of the switchover period based on the relative humidity of supply air, and control of compressor frequency based on evaporation and condensation temperature is established. By using the optimal operation strategies, the dehumidification rate and COP of the system can reach 4.42 kg/h and 6.2 in summer, compared with the unoptimized strategy it increased 8% and 25%, respectively. The two performance indices can reach to 3.04 kg/h and 6.98, with an increase of 89% and 78%.

Transient simulation and experimental analysis for the response of dual-cycle air-carrying energy radiant diffuse terminal

A novel air-carrying energy radiant diffuse terminal is proposed, and the response of the terminal is investigated by field experiment and numerical simulation. This paper explores the dynamic operation characteristics of the new system to guide the optimal operation of the system. A transient simulation method of three factors (conduction, convection, and radiation) with dual-circulation (air-carrying energy zone and occupied zone) is put forward for the radiant diffuse terminal with a fresh air system. This transient simulation sets up the porous baffle model coupling radiation model concurrently, revealing the dynamic thermal performance for the system's response accurately, quickly, and comprehensively. This method avoids the limits for the complexity of mini porous (Pore size of 1 mm–3mm) geometric models and the transient uncertainty in multiple combination models. The results show that the average error between the convective-conductive model and the convective-conductive-radiative model is about 8% at five different heights. This system has high response performance, which can quickly heat the room while maintaining the comfort requirements of vertical temperature. The radiated heat transfer between the radiant diffuse terminal and the occupied zone is greater than the convective heat transfer (Radiation accounts for 74%). This system has a short response time, high energy efficiency, uniform airflow, and eliminates draught rating. Moreover, the indoor non-uniform transient thermal and humid environments, the thermal comfort, and air quality for the response of the terminal with fresh air system under four different diffuser placements are compared using computational fluid dynamic simulation. The results indicate that introducing heating strategies featuring higher-positioned fresh air inlet and lower-positioned recirculation return air outlet for this system leads to a temperature efficiency increase by 5%, velocity uniformity by 8%, and age of air reduction by 16–50% in human-breathed zone and the response time by 25%, which shows substantial potential for energy savings. The transient simulation and experiments in the paper are beneficial to optimize design parameters and carry out energy-saving applications of operation energy consumption for the response of this terminal with a fresh air system in the future.

Design and performance analysis on a breathing-type instant heat recovery module for fresh air ventilation

The process of air exchange in buildings is essential for maintaining optimal indoor air quality. However, this process results in the loss of thermal energy in the form of sensible heat carried by the air, thereby increasing the energy demand of the buildings. In order to recover this thermal energy, the present study introduces a breathing-type instant heat recovery module for fresh air ventilation, inspired by the biological nasal breathing process. The performance of this module was thoroughly investigated through Fluent simulation and experimental tests. Based on the simulation results, the module exhibits the capability to decrease the outdoor air temperature by an average of 7.5 ℃ prior to its entry into the room. Consequently, this leads to a daily energy conservation of approximately 2.354 kW·h, accompanied by an energy recovery rate of 62.9 % under typical summer conditions. Notably, the heat recovery performance is more favorable during winter, resulting in daily energy savings of about 5.446 kW·h and an energy recovery rate of 62.2 %. The conducted experiments substantiate that the module is able to recuperate approximately 70 % of heat when the indoor temperature is set at 22 °C, while the outdoor temperature reaches its lowest point at 6 °C. The study describes an effective heat recovery technology for building air exchange using a breath-type instant heat recovery module. This could offer a new energy-saving solution for the renovation of fresh air systems.

Evaluation and prediction of fibrous filters' operating performance in residential fresh air system

Fibrous filters play a crucial role in determining indoor air quality and protect people from bacteria, particulates, and viruses such as COVID-19. However, there is a lack of comprehensive research on methods for effectively evaluating and predicting the operating performance of these filters. In this study, we conducted laboratory and field tests on coarse (G4) and medium (F9 or F7) filters from four different brands to assess both their initial and operating performance. We discovered that a fluffy fiber structure in coarse filters could achieve an impressive threefold increase in dust holding capacity (DHC) compared to normal filters. Utilizing initial pressure drop, initial particle capture efficiency, and DHC, we introduced a new quality factor (QF) that integrates these parameters to evaluate the filter's long-term performance. This approach addresses the limitations of traditional quality factor, which neglects DHC and tends to underestimate the performance of filters with high DHC. Additionally, we proposed a simple method to predict the filter's operating pressure drop, using particle concentration data from weather report. This allows for convenient assessment of the fresh air system's operating status, offering potential integration into a user-friendly mobile application or computer software. These findings contribute innovative ideas for enhancing the intelligent and energy-efficient operation of fresh air systems.

Start-up strategy analysis of capillary network radiant cooling-assisted fresh air system based on intermittent operation

The capillary network radiation cooling system has received wide interest recently because of its high comfort potential, but the problem of condensation hinders its applications. In this regard, integrating a fresh air dehumidification system can effectively address the problem of condensation. Three start-up strategies of a capillary network radiant cooling-assisted fresh air system are proposed in this study, considering the typical initial working conditions in the Wuhan region. The optimal starting strategy of the coupled system is examined and discussed using numerical simulations. The results showed that under conditions of high temperature and high humidity, the strategy of opening the capillary tube only after the dehumidification of the fresh air system reaches 18 °C should be adopted. Under other conditions, the optimal strategy is to use the fresh air system to deliver both dehumidification and cooling until the dew point temperature of the attached layer attains 18 °C and then turn on the capillary network. Moreover, the synchronous start-up strategy of starting the fresh air system and opening the capillary network should be adopted under the conditions of high temperature and high humidity, and low temperature and high humidity. In this case, the temperature of the capillary water supply is controlled to decrease to about 18 °C at a temperature drop rate of 0.2 °C/min. For the high temperature and low humidity conditions, the water supply temperature should be controlled at a temperature drop rate of 1.2 °C/min, which can achieve a better anti-condensation effect. This study can provide theoretical guidance and supporting information for the actual start-up strategy of the coupled system under different indoor and outdoor temperature and humidity conditions.

Outdoor design PM2.5 concentration method for fresh air systems based on dual-carbon target: A case study of urban economic regions from China

Under the goal of ?achieving carbon peak by 2030 and carbon neutrality by 2060?, how to select the type of fresh air system has become a key area of ener?gy conservation. The method of outdoor design PM2.5 concentration is one of the important factors affecting the selection of fresh air filtration system. This paper first analyzed the PM2.5 concentration values of 31 cities in China from 2017 to 2020 based on mathematical induction, and next gave the recommended coeffi?cient K under six urban economic regions methods in combination with the actual situation. Finally, the selection of air filters in five typical cities was taken as an example, the differences in recommended coefficient K and selection of outdoor design PM2.5 concentration under different recommended methods were compared and analyzed. The results showed that the recommended coefficient K under the six economic regions could meet the required K value needs of the region. The recommended coefficient K by the six economic regions methods based on per capita GDP is the best. Under that conditions, the recommended coefficient K of the five typical cities under strict and normal conditions differs from the average K values of the six methods by 0.06 and 0.04. This paper will provide a new method for the correct selection of outdoor design PM2.5 concentration in fresh air systems to achieve the dual carbon energy-saving goal.

Deposition rate and purification effect of atmospheric particle by different pipeline connection forms

The connection form of pipelines has an important impact on the comprehensive performance evaluation of fresh air systems. The most used PVC fresh air pipeline material in the market was selected for experimental research in this paper, and the deposition rates of particles of different pipeline connection form of 45?, 90? bend, and straight tee were all tested and compared. The purification effect of the pipeline connection form of the highest deposition rate is tested and studied. The results showed that the particle deposition rates were the highest in the connection form of straight tee, with deposition rates of 47.61%, 18.06%, and 8.13% for PM10, PM2.5, and PM1.0, respectively. As the particle size increases, the deposition rate of particles also gradually increases. The larger the inlet velocity, the greater the deposition rate. The particle concentration on the outlet of the pipeline in the connection forms of straight tee was significantly decreased after adding the purification equipment, and the deposition rates of PM10, PM2.5, and PM1.0 decreased by 45.01%, 68.89%, and 77.48%. Therefore, the use of pipeline elbows should be reduced, and purification equipment should be installed in the process of using, which will reduce the deposition of particles in the fresh air systems.