Air Flow Rate Research Articles

Airflow Characteristics in Conveyor Type Damper for Hot Air Temperature Changes

The aim of this study was to present the characteristics of a hot airflow in a conveyor type dampers under the hot air temperature changes. The amount of space occupied by the damper was reduced by 50 %, and by efficiently managing the damper's airflow rate even in the face of extreme external conditions and constant air volume proportional control, a conveyor-type damper with a significant energy-saving effect has been explored. It was configured to control the degree to which it was opened by operating the folding conveyor drive mechanism, enabling the damper to modify airflow. In this study, the mass flow rate of heated air through the conveyor-type damper increased in proportion to the damper port's expansion. The mass flow rate of air decreased as the temperature of air intensified. In addition, the thermal energy of the air flowing in the conveyor-type damper improved in ratio to the increase in the damper opening. The findings indicate a 50 % reduction in the damper's occupied space, indicating a significant energy-saving impact of the conveyor-type damper. This is because the damper's air volume is effectively controlled even in the face of severe external conditions, as it is proportionately controlled throughout. The understanding of the properties of airflow for the hot temperature change is strengthened by this research. Furthermore, this study may provide useful direction for future research and industry optimization.

Experimental study on thermal performance of reverse flow solar collector for dual heating applications

AbstractThe present study investigated the performance of dual function reverse flow solar collector (RFSC). The impact of the mass flow rate of air and water on outlet temperature, thermal performance, and overall performance of dual‐function solar air heater (SAH) has also been investigated. An experimental investigation of three different working models namely, Model‐A: SAH, Model‐B: solar water heater (SWH), and Model‐C: integrated solar air‐water heater (SAWH) for dual heating applications was performed to analyze the actual performance of these models. The investigation of the impact of time intervals on the water inlet and outlet temperatures at various mass flow rates of water is conducted to analyze the time‐varying efficiency of SWH systems. Furthermore, the effect of solar intensity on the performance of the dual‐function heating system has also been explained. The result reveals that the maximum thermal efficiency of Models: A and B can be achieved at about 78.8% and 67.9%, at a mass flow rate of 0.0644 and 0.10 kg/s, respectively, according to the experimental findings. The maximum temperature rise of air and water reaches about 52.4 and 55.58°C for Models A and B, respectively. The total efficiency of Model C reaches 81.69%, exceeding that obtained in Models A and B individually. The efficiency, outlet temperature of the fluid, and heat transfer effectiveness of the system strongly depend on the mass flow rate. The increase in heat removal factor is negligible for a higher flow rate (more than 0.10 kg/s).

Internal temperature prediction and control strategy design of anode-supported solid oxide fuel cell for hot start-up process

Anode-supported solid oxide fuel cell (SOFC) has a high energy efficiency while suffering from a poor transient performance such as start-up. In this study, a model-based design method is proposed to develop a suitable strategy for the rapid hot start-up of anode-supported SOFC (AS-SOFC). First, a mathematical model is established for a 25-kW SOFC system and the internal temperature is predicted. Subsequently, three different strategies are compared during hot start-up process. The results indicate that the positive-electrolyte-negative (PEN) temperature variation magnitude is 50 K and the response time is 1300 s when the hydrogen and the air flow rates are fixed for the afterburner and the cathode. If a PID controller is employed to regulate the flow rate of H2 to the afterburner, the PEN temperature variation magnitude decreases to 16 K with a shorter response time of 158 s. When increasing the air flow rate synchronously, the PEN temperature variation magnitude is merely 8 K, reduced by 84 % and 50 % compared with the previous strategies. Additionally, the gas temperature exiting from the afterburner declines significantly for the third control strategy. Thus, the lifetime and reliability of AS-SOFC is enhanced. The results provide a reference for the SOFC systems control such as domestic combined heat and power (CHP) and mobile applications.

Effects of dust loading on the long-term performance of portable HEPA air cleaner to woodsmoke – A laboratory investigation

Portable air cleaners (PACs) equipped with high-efficiency particulate air (HEPA) filters are recommended to reduce indoor particulate matter (PM) exposure from wildfire smoke, particularly in regions like the Pacific Northwest, where seasonal wildfires affect air quality. While many studies have evaluated the long-term effectiveness of HEPA PACs, few have focused on the effects of dust loading and their performance in filtering woodsmoke over extended periods. This study investigated the impact of filter dust loading on the performance of a HEPA PAC (Winix C535, Winix America) in reducing woodsmoke particles. Filters were pre-loaded with varying amounts of ASHRAE ISO 12103–1 A2 fine test dust, and an exposure chamber was used to assess clean air delivery rate (CADR), airflow rate, and power consumption. Results indicated a significant decline in PAC performance with increasing filter loading, highlighting the importance of regular filter replacements to maintain effective operation. Based on simulations considering dynamic indoor PM2.5 concentration, in a typical scenario with a 90-m² room, baseline PM2.5 emission rates, and continuous operation at fan speed Level 2 (5-year mean indoor PM2.5: 2.99 μg/m3), it would take over 5 years for the PAC filters to accumulate 46 g of dust – an amount associated with a significant drop in CADR observed in the study. These findings suggest that the commonly recommended 1-year replacement schedule by manufacturers may be overly conservative for such conditions. By utilizing indoor air quality sensors to monitor PM concentrations, users can tailor filter replacement schedules to maintain optimal PAC performance in real-world environments.

Loss and Thermal Analysis of a High-Power-Density Permanent Magnet Starter/Generator

Reducing heat and improving the overall operation stability of the motor play a key role in the design of a starting engine. This paper focuses on the loss and thermal analysis of a permanent magnet (PM) brushless machine used in starter generators. The loss of the starter generator was calculated through a combination of theoretical analysis and the finite element method. A thermal analysis model was established based on the division of the fluid domain, boundary grid, heat source setting, and so on. The temperature fields of the whole motor and the main components were calculated and analyzed. The main factors affecting the air cooling effect were analyzed, including air flow rate, air temperature, and motor speed. A prototype experimental platform of the SG motor was built. The efficiency and temperature rise in the motor were tested. The temperature values were compared with the calculated values. The experimental results show that the performance of the motor is excellent, and the error between the temperature and the design calculation is less than 10% under each load torque. The accuracy of the thermal analysis method is verified. The correctness of the motor transient model was also confirmed through a temperature rise experiment under rated conditions, providing a research basis for improving operation efficiency.

Impacts of non-uniform airflow over gas cooler on the performance of transcritical CO2 air conditioning

The air flowrate and air inlet temperature over gas cooler in transcritical CO2 air conditioning for vehicles are easily unevenly distributed due to the influence of upstream obstacles. The unevenly distributed airflow affects heat exchange between CO2 and air, thus influencing the cooling capacity and power consumption of the air conditioning system. This study delves into the implications of such non-uniform airflow on the operational performance of transcritical CO2 air conditioning through simulation analysis. It elucidates the mechanisms by which the uneven distribution pattern, uneven distribution direction and non-uniformity affect the cooling capacity of transcritical CO2 air conditioning system. Moreover, the conditions of inhomogeneous airflow for enhanced heat transfer are explored by decoupling inhomogeneous flow rate and inhomogeneous temperature. Results indicate that non-uniform airflow of air temperature distributed as TB-HT (high in top and low in bottom) and air flowrate as TB-HB (high in bottom and low in top) increases the cooling capacity of 27.7 % at non-uniformity of 55 %. Conversely, uneven airflow of flowrate and temperature both distributed as LR-HL (high in left and low in right) at 40 % non-uniformity leads to a wastage of compressor power up to 1/2. These findings reveal the dual impacts of non-uniform airflow on the performance of transcritical CO2 air conditioning system, which emphasizes the importance of considering these impacts when designing automotive CO2 air conditioning systems.

Multi-scenario surveillance of respiratory viruses in aerosols with sub-single-copy spatial resolution

Highly sensitive airborne virus monitoring is critical for preventing and containing epidemics. However, the detection of airborne viruses at ultra-low concentrations remains challenging due to the lack of ultra-sensitive methods and easy-to-deployment equipment. Here, we present an integrated microfluidic cartridge that can accurately detect SARS-COV-2, Influenza A, B, and respiratory syncytial virus with a sensitivity of 10 copies/mL. When integrated with a high-flow aerosol sampler, our microdevice can achieve a sub-single-copy spatial resolution of 0.83 copies/m3 for airborne virus surveillance with an air flow rate of 400 L/min and a sampling time of 30 minutes. We then designed a series of virus-in-aerosols monitoring systems (RIAMs), including versions of a multi-site sampling RIAMs (M-RIAMs), a stationary real-time RIAMs (S-RIAMs), and a roaming real-time RIAMs (R-RIAMs) for different application scenarios. Using M-RIAMs, we performed a comprehensive evaluation of 210 environmental samples from COVID-19 patient wards, including 30 aerosol samples. The highest positive detection rate of aerosol samples (60%) proved the aerosol-based SARS-CoV-2 monitoring represents an effective method for spatial risk assessment. The detection of 78 aerosol samples in real-world settings via S-RIAMs confirmed its reliability for ultra-sensitive and continuous airborne virus monitoring. Therefore, RIAMs shows the potential as an effective solution for mitigating the risk of airborne virus transmission.

A multiphase flow model of water droplets dielectrophoretic-induced air dehumidification phenomena

Air humidity in indoor spaces plays a critical role in human comfort and health. Dehumidification systems are used for building humidity controls, but they can take significant energy consumption, especially in geographic locations with high outdoor humidity and warm climates. Consequently, there is a growing demand for innovative dehumidification processes that consume minimal energy. Dielectrophoretic air dehumidification represents one such promising approach. However, it has not garnered significant attention due to the absence of engineering models and simulation tools capable of evaluating its performance and limitations at large-scale airflows. A new numerical multiphase CFD model, which is also experimentally validated, is developed in a customized Reacting Foam solver based on OpenFOAM® version 9. The newly developed model seeks to decrease substantial energy consumption and lower costs by leveraging the dielectrophoretic phenomenon to regulate moisture levels in the air. The solver integrates a hybrid Eulerian-Lagrangian framework to track the droplet's trajectory and growth rate while solving the continuum equations for the moist air. An electrospray produces electrically charged droplets, which grow during their in-flight trajectories as water vapor condenses onto their surfaces. The role of electrostatic forces in promoting vapor condensation within a high-gradient electrical field is investigated, and the dielectrophoretic vapor nucleation process on charged water droplets is discussed. The CFD model was validated against results from the literature and from proof-of-concept experiments conducted by the authors, which showed a 2 % air dehumidification with a single electrospray and airflow rate of 5 cubic feet per minute. The simulation results indicated that augmenting the number of electrically charged spray droplets increased the dehumidification of the air to 25 %. The initial mean droplet diameter, the orientation of the injector and relative humidity significantly influence the assessment of dehumidification. Scaling up this approach to larger airflow volumes is identified as a potential future research direction.

Mesh Refinement for Dynamics Airflow in Health Care

This studyexplores using computational fluid dynamics(CFD) tooptimize ventilation in healthcare, with a focus on mesh refinement for accurate airflow analysis. The goal is to reduce airborne contaminant spread, which is crucial during COVID-19. Ventilation in healthcare ensures air quality and minimizes pathogen transmission. The research analyzer analyzes mesh element size's impact on airflow accuracy in simulated hospital wards with two coughing patients. The optimal mesh size is determined for reliable predictions. Mesh refinement enhances accuracy in critical zones. The k-epsilon turbulence model is chosen for low error. Experimental validation shows temperature discrepancies, likely due to simulated manikins lacking clothing insulation. Air velocity measurements show minor variations within an acceptable range. Further research on various ventilation configurations and airflow rates in real hospital conditions is crucial. Addressing these limitations optimizer optimizeshealthcare ventilation, enhancing safety and infection control.

Night cooling by hybrid supply ventilation – analytical predictions of airflow rates and the ‘hybrid ventilation triangles’

Overheating in buildings can be mitigated during periods of excessively warm weather through the application of a night purge ventilation strategy. Building on the mathematical model of Waterson and Hunt (2024), we investigate the emerging field of hybrid ventilation – specifically the rates of airflow achieved by the simultaneous combination of ‘stack-driven’ natural displacement ventilation and a mechanical supply. Whilst the focus of Waterson and Hunt (2024) was specifically on predicting the time taken to complete a purge, herein we focus on airflow rates and in doing so elucidate the somewhat counter intuitive role that the mechanical supply has on the natural ventilation flow rates. Our results challenge the perception that a hybrid approach must be superior to both solely natural and mechanical strategies. Focusing on the variation in airflow rates during a hybrid purge, our model reveals: (i) a hybrid purge offers an improvement over a solely mechanical purge only during one of the two distinct flow regimes identified; and (ii) the manner in which the stack-driven and mechanical components combine is highly nuanced and cannot be predicted by the linear superposition of the constituent stack-driven and mechanical contributions.

Optimizing light intensity and airflow for improved lettuce growth and reduced tip burn disease in a plant factory

In practical plant factory production, light intensity and airflow were major environmental factors that significantly impacted lettuce growth and tip burn disease. This study investigated the effects of light intensity (100, 200, and 300 μmol·m-2·s-1) and airflow rate (100, 200, and 300 m³/h) on the comprehensive quality of lettuce. The Analytic Hierarchy Process (AHP) was employed to determine the weight of various growth and physiological indices of lettuce, while fuzzy mathematics principles were used to evaluate its comprehensive indices. The findings revealed that higher light intensity increased Ca2+ demand and decreased stomatal conductance, exacerbating tip burn disease. In contrast, increasing the airflow rate reduced leaf temperature, promoted transpiration, and facilitated calcium ion transport, thereby alleviating the occurrence of tip burn. Increasing the airflow rate to 300 m³/h effectively improved plant transpiration and Ca²⁺ transport, which further reduced tip burn. The comprehensive results indicated that under the conditions of a light intensity of 200 μmol·m-2·s-1 and an airflow rate of 300 m³/h, lettuce achieved the best comprehensive quality score of 0.6490, with a Ca2+ content of 21.83 mg/100 g, and tip burn was effectively suppressed. The study provided valuable scientific support for the precise control of environmental conditions in plant factories.

Controllable generation of engine exhaust similar soot particles using an inverted nitrogen-diluted flame burner for calibration purpose

The calibration of vehicle engine exhaust PN analyzers has been a challenge due to the significant difference in properties between calibration particles and measured particles. In this study, an inverted nitrogen-diluted flame burner was designed to generate engine exhaust similar soot particles and evaluated for calibration use. The burner can produce reference-unimodal soot particles at 61–311 nm and total number concentration up to 108 #/cm3 by adjusting the flow rate of ethylene, nitrogen and air. Excellent stability of 0.91 % enables it to generate a fairly stable calibration particle flow. Mixing nitrogen in ethylene makes burner have a high degree of variability in generating smaller particles. The properties of size distribution, morphology, effective density indicate that the generated soot particles can simulate well with engine exhaust particles. TOA results indicate that the soot have high TC mass concentration of over 559.26 mg/m3 and EC/TC fraction of over 90 %.

Experimental study of the design and performance optimisation of a self-heating methanol on-board reforming reactor for hydrogen production

There is an increasing research on efficient and compact on-board reformer, based on which a serpentine plate type self-heating reformer integrating preheating, reforming and combustion has been designed and fabricated, which can be disassembled and assembled flexibly. In this paper, experiments on the self-heating reformer have been carried out to optimise the differential structure of different chambers. It can be found that: the combustion chamber needs to be partitioned and the resistance loss is small and stable for a long time when the number of partitions is 3. The combustion chamber with O2/CH3OH = 1.5 has the highest wall temperature of 240 °C. Hydrogen yield can be increased to more than two times after optimising the evaporation chamber. The catalyst in the reforming chamber must be uniformly distributed, and the methanol conversion rate is stable at 75 % with a mass of 110 g and Weight Hourly Space Velocity (WHSV) = 8 h−1. The optimum operating conditions of the reactor is WHSV = 8 h−1 with air flow rate of 25 L/min, at which the reactor starts up within 20 min, the hydrogen yield stabilises within 40 min, and the hydrogen yield is 9.8 L/min and remains stable for 120 min.

Real-time monitoring of integrated continuous granulation/drying line system “LaVortex®” for the pharmaceutical manufacturing of acetaminophen oral dosage formulations using near-infrared spectroscopy

Granules for tableting were continuously manufactured using a fully flow-type continuous wet-granulation and drying (CGD) line system, “LaVortex®.” The raw material powder containing standard excipients and 28.8 % acetaminophen was mixed with a binder liquid (pure water), continuously wet-granulated, and dried for 600 s under 20 different granulation/drying process conditions, and the process was monitored in real-time using near-infrared (NIR) spectroscopy. Twenty granulation/drying process conditions, varying across three parameters, namely added binding water rate, agitation blades and container rotational rates, and hot drying air flow rate, were applied. Training datasets from NIR spectroscopy stably measured during the CGD process were used to construct calibration models to predict the various critical quality attributes (CQAs) of granules, such as residual moisture content, median particle size, angle of repose, and tablet hardness, using partial least squares regression (PLSR). Optimal calibration models were validated using the NIR spectroscopy test dataset. The actual granule CQA profiles evaluated using the NIR/PLSR method were almost constant up to 600 s at the end of production depending on the critical process parameters (CPPs), except for fluctuations in the initial process. These results indicate that tableting granules with various pharmaceutical properties could be obtained continuously depending on CQAs, such as the rate of water addition. Additionally, changes in CQAs could be continuously monitored by the NIR/PLSR method. Furthermore, CGD granules with various characteristic CQAs can be continuously manufactured by controlling CPPs, such as agitation blades and tube rotation rates in the agitating granulation process and drying air flow rate in the drying process under NIR spectroscopy.

Influence of microbubble two-phase feed flow on reverse osmosis desalination using different salt concentrations

This study aims to implement microbubble two-phase flow in the feed stream to improve mass transfer and achieve improved reverse osmosis (RO) process performance. The swirl-flow microbubble generator (MBG), which can effectively generate microbubbles, is integrated into the conventional RO system and has experimentally proven its performance under various operating conditions. To investigate the influence of microbubbles in the feed stream on the RO process depending on the feed concentration, real seawater and two types of artificial brackish water were used as the feed solution. The formation of microbubble two-phase flows in the feed stream had a positive impact on the transmembrane flux and distillate water quality of the RO process; this demonstrates that improved mass transfer due to microbubbles introduced into the feed can effectively attenuate the concentration polarization effect in the RO process. MBG-RO performance using seawater as the feed solution was found to be more pronounced at lower feed pressures and higher airflow rates, with an improvement in permeation flux of up to 16 %. Meanwhile, the MBG contribution to RO performance was lower when using artificial brackish water with relatively low concentration than that when using seawater.

Thermal and exergy analysis of solar air heater enhanced with sodium carbonate decahydrate and Magnesium sulfate heptahydrate PCM: Performance evaluation

The advancement of renewable solar energy is prospective for energy, heat exchanger, and air heater applications. The main objective of the present research is enhancing the solar air heater thermal performance by the modification of a collector absorber-like plain absorber featuring rectangular fine (SAH 2) and sodium carbonate decahydrate (Na2CO3·10H2O) and Magnesium sulfate heptahydrate (MgSO4·7H2O) PCM with rectangular fin (SAH 3). During the experimental evaluation, the airflow varied by 0.042 and 0.059 kg/s. Influences of collector modification on the functional behaviour of solar air heaters (SAH) are evaluated. Its results are compared to the system of conventional setup without modification of the solar collector with a plain absorber (SAH-1). With the excellence of Na2CO3·10H2O/MgSO4·7H2O with fin setup performed with 0.059 kg/s found better heat transfer performance including heat gain, thermal & exergy efficiency, heat loss coefficient, and PCM temperatures like 927.3 W, 78.6 %, 33.6 %, 16.9 W/m2K, and 68.3 ⁰C respectively. Moreover, Increasing the airflow rate leads to improved heat transfer, and the SAH proves to be effective at higher flow rates when equipped with fins and PCM.

Experimental investigation and mathematical modelling of the heat and mass transfer processes in a solar chimney

Solar chimney is one of the solar energy-based techniques, and the phenomenon of mass transfer usually occurs in solar chimney, which has not received enough attentions to date. The aim of this paper was to develop a mathematical model of solar chimney considering both heat and mass transfer processes. Both experimental and analytical results indicated that mass transfer has a great influence on the system ventilation performance. Furthermore, the mathematical modelling revealed that the integral mean air temperature was decreased by 18.70 %, while the airflow rate was reduced by 70.40 %, when the area ratio increased from 0.10 to 0.65. Additionally, the airflow disappeared as the area ratio was further increased to 0.70. The airflow rate was increased by 70.70 %, and the integral mean air temperature was increased by 2.50 °C when the relative humidity increased from 10 % to 90 %. The integral mean air temperature was increased by 92.20 %, while the airflow rate was only increased by 1.90 % when the ambient temperature increased from 20 to 40 °C. The study provided a more accurate theoretical approach for the optimal design and prediction of ventilation performance of the solar chimney.

Modulating phytoremediation: How drip irrigation system affect performance of active green wall and microbial community changes

A recent innovation in air phytoremediation is active green walls, which utilises biofiltration technology with airflow from mechanical ventilation. While this novel technology is gaining traction, the influence of irrigation on soil moisture, and subsequently the microbial communities that play a role in air filtration is untested. In this study, the application of drip irrigation techniques in active green walls were investigated for their influence on system performance. A modular green wall system was tested, with tests across 7 different plant species, as well as a substrate only control. Water distribution across the modules, the water-carrying capacity and airflow through the substrate were measured. The microbial community present, which is critical to the phytoremediation process, was quantified by identifying individual microbial phospholipid fatty acids (PLFA) within the substrate. Results demonstrated that the lower-speed drip irrigation reduced water consumption compared to the rapid system, and had generally more uniform moisture distribution. High flow drip irrigation resulted in a water pathway phenomenon, leading to uneven moisture distribution within the green wall, and this effect was accentuated with fibrous root plant species. Drip irrigation did not change microbial community composition across planted modules, apart from increasing fungi by 6%, but did wash out bacteria at the high flow rate used (−56.67%), thus low flow rate irrigation rate is more beneficial for both plant growth and microbial community composition. The current work provides evidence that drip irrigation has considerable effects on both substrate airflow rate and substrate microbial density: both key to system air cleaning performance.

Indoor environmental quality assessment in passively ventilated classrooms in Germany and estimation of ventilation energy losses

In this field study we present an approach for the comprehensive and room-specific assessment of parameters with the overall aim to realize energy-efficient provision of hygienically harmless and thermally comfortable indoor environmental quality in naturally ventilated non-residential buildings. The approach is based on (i) conformity assessment of room design parameters, (ii) empirical determination of theoretically expected occupant-specific supply air flow rates and corresponding air exchange rates, (iii) experimental determination of real occupant-specific supply air flow rates and corresponding air exchange rates, (iv) measurement of indoor environmental exposure conditions of T, RH, cCO2, cPM2.5 and cTVOC, and (v) determination of real energy demands for the prevailing ventilation scheme. Underlying assessment criteria comprise the indoor environmental parameters of category II of EN 16798-1: Temperature T = 20 °C–24 °C, and relative humidity RH = 25 %–60 % as well as the guide values of the German Federal Environment Agency for cCO2cPM2.5 and cTVOC of 1000 ppm, 15 μg m−3, and 1 mg m−3, respectively.Investigation objects are six naturally ventilated classrooms of a German secondary school. Major factors influencing indoor environmental quality in these classrooms are the specific room volume per occupant and the window opening area. It is concluded that the rigorous implementation of ventilation recommendations laid down by the German Federal Environment Agency is ineffective with respect to anticipated indoor environmental parameters and inefficient with respect to ventilation energy losses on the order of about 10 kWh m−2 a−1 to 30 kWh m−2 a−1.

Performance analysis of a conventional two-stage indirect evaporative cooler

With the aim of saving a portion of the high-quality energy consumed in mechanical vapor compression systems for air conditioning applications, the present work focuses on utilization of low-quality energy conversion processes due to fluid evaporation. The conventional indirect evaporative cooler is selected based on its preference for further modification compared to a regenerative indirect evaporative cooler. It is configured to be operated with two identical stages in series. This task is achieved by developing a thermodynamic model to analyze the performance of the cooling unit and to indicate the extent of its development compared to the cooler in one stage. Preliminary results show that the best operating condition is when the ratio of primary air to secondary air is 1. The cooling unit produces fairly comfortable air within limited climatic conditions. It delivers air at 26 °C and lower even at climatic temperatures as high as 48 °C, but within a very low relative humidity range. The relative humidity range extends to less than 58% as the outdoor air temperature decreases. At high humidity levels (64 to 80% depending on climate temperature), cool air cannot be obtained at 26 °C, and the cooling unit performance is limited only by what the first stage produces. The average performance of the cooling unit exceeds that of the first stage by 42.6%. Increasing air flow rate leads to an increase in cooling capacity, but it also has a negative impact on supply temperature and effectiveness.