Floor Supply Research Articles

A Comparative Analysis of Machine Learning Algorithms in Predicting the Performance of a Combined Radiant Floor and Fan Coil Cooling System

Machine learning algorithms have proven to be practical in a wide range of applications. Many studies have been conducted on the operational energy consumption and thermal comfort of radiant floor systems. This paper conducts a case study in a self-designed experimental setup that combines radiant floor and fan coil cooling (RFCFC) and develops a data monitoring system as a source of historical operational data. Seven machine learning algorithms (extreme learning machine (ELM), convolutional neural network (CNN), genetic algorithm-back propagation (GA-BP), radial basis function (RBF), random forest (RF), support vector machine (SVM), and long short-term memory (LSTM)) were employed to predict the behavior of the RFCFC system. Corresponding prediction models were then developed to evaluate operative temperature (Top) and energy consumption (Eh). The performance of the model was evaluated using five error metrics. The obtained results showed that the RF model had very high performance in predicting Top and Eh, with high correlation coefficients (>0.9915) and low error metrics. Compared with other models, it also demonstrated high accuracy in Eh prediction, yielding maximum reductions of 68.1, 82.4, and 43.2% in the mean absolute percentage error (MAPE), mean squared error (MSE), and mean absolute error (MAE), respectively. A sensitivity ranking algorithm analysis was also conducted. The obtained results demonstrated the importance of adjusting parameters, such as the radiant floor supply water temperature, to enhance the indoor comfort. This study provides a novel and effective method for evaluating the energy efficiency and thermal comfort of radiant cooling systems. It also provides insights for optimizing the efficiency and thermal comfort of RFCFC systems, and lays a theoretical foundation for future studies integrating machine learning algorithms in this field.

Improved Chimp Optimization Algorithm for Matching Combinations of Machine Tool Supply and Demand in Cloud Manufacturing

Cloud manufacturing is a current trend in traditional manufacturing enterprises. In this environment, manufacturing resources and manufacturing capabilities are allocated to corresponding services through appropriate scheduling, while research on the production shop floor focuses on realizing a basic cloud manufacturing model. However, the complexity and diversity of tasks in the shop floor supply and demand matching environment can lead to difficulties in finding the optimal solution within a reasonable time period. To address this problem, a basic model for dynamic scheduling and allocation of workshop production resources in a cloud-oriented environment is established, and an improved Chimp optimization algorithm is proposed. To ensure the accuracy of the solution, two key improvements to the ChOA are proposed to solve the problem of efficient and accurate matching combinations of tasks and resources in the cloud manufacturing environment. The experimental results verify the effectiveness and feasibility of the improved ChOA (SDChOA) using a comparative study with various algorithms and show that it can solve the workshop supply and demand matching combination problem and obtain the optimal solution quickly.

Experimental study on the control effects of different strategies on particle transportation in a conference room: Mechanical ventilation, baffle, portable air cleaner, and desk air cleaner

To control the spread and transmission of airborne particles (especially SARS-CoV-2 coronavirus, recently) in the indoor environment, many control strategies have been employed. Comparisons of these strategies enable a reasonable choice for indoor environment control and cost-effectiveness. In this study, a series of experiments were conducted in a full-scale chamber to simulate a conference room. The control effects of four different strategies (a ventilation system (320 m3/h) with and without a baffle, a specific type of portable air cleaner (400 m3/h) and a specific type of desk air cleaner (DAC, 160 m3/h)) on the transportation of particles of different sizes were studied. In addition, the effects of coupling the ventilation strategies with five forms of indoor airflow organization (side supply and side or ceiling return, ceiling supply and ceiling or side return, floor supply and ceiling return) were evaluated. The cumulative exposure level (CEL) and infection probability were selected as evaluation indexes. The experimental results showed that among the four strategies, the best particle control effect was achieved by the PAC. The reduction in CEL for particles in the overall size range was 22.1% under the ventilation system without a baffle, 34.3% under the ventilation system with a baffle, 46.4% with the PAC, and 10.1% with the DAC. The average infection probabilities under the four control strategies were 11.3–11.8%, 11.1–11.8%, 9.1–9.5%, and 18.2–19.7%, respectively. Among the five different forms of airflow organization, the floor supply and ceiling return mode exhibited the best potential ability to remove particles.

A Dynamic Model of Floor Supply With Land Use Regulation

A Dynamic Model of Floor Supply With Land Use Regulation

Performance evaluation of different air distraction system on thermal uniformity and energy saving: A case study of a Japanese detached house

Heat shock is generated from zonal temperature differences. The pre-heating control through an air conditioning system can provide a good thermal environment, and reduce the risk of suffering heat shock in a house and with low energy consumption. In this study, a room air-conditioner (RAC) and air recirculating fan system (ARF) connected to the temperature zone of living room and washing room are applied in a detached house. The design aims to reduce the overconsumption of system energy and fulfil the healthy demand. With low air supply velocity (0.5 m/s) of ARF, the floor supply case can produce a saving of 33.9% energy for RAC to reach the target temperature 20°C in wash room (0.8 m height) in comparison to the ceiling supply case. However, return opening located on the floor was closer to RAC compared to ceiling case, hence, place of return opening should be accounted for energy reduction rate relatively.

PIV experiment and evaluation of air flow performance of swirl diffuser mounted on the floor

In order to obtain satisfactory effect of air conditioning and ventilation, the floor–supply displacement ventilation has widely applied in many civil buildings. Swirl diffusers mounted on the floor are widely used to provide fresh air into the occupied zone in the floor–supply displacement ventilation system. This paper studied the air distribution performance of swirl diffuser by 2D-PIV (particle image velocimetry). The experiment was implemented in a full-scale room to achieve reliable data of swirl diffusers. Flow visualizations have been carried out to determine the shape of the swirl jet. The whole velocity field was measured by 2D-PIV system, which is very useful to analyze air distribution above the swirl diffuser. With the aid of the flow visualizations and PIV test technology, the macro and micro structure of the air flow above the swirl diffuser is specified in more detail. Moreover, the centerline velocity decay coefficient (K value) and entrainment ratio were obtained. The research work of this paper provides detailed experimental data of air flow above the swirl diffuser, which provide the reference for selection of air terminal devices and a basis for follow-up numerical simulation study.

Experimental Study of Airflow Designs for Data Centers

Growth in ICT has led to increased demands on data centers. Highly reliable operations of data centers require an efficient and robust air-conditioning system. In most data centers, circulating air enters at the floor level, and returns at the ceiling level (floor supply design). However, the authors have developed an airflow design in which air is both supplied and returned at the ceiling level (ceiling supply design). To compare the cooling characteristics of both designs, temperatures were measured in a full-scale model of a data center. For both designs, changes in cooling characteristics were evaluated in response to changes in heat density, supply-air volume, and supply-air temperature. In addition, the authors studied the effects of separating cold and hot aisles by hanging walls from the ceiling between aisles. Dimensionless indices, dimensionless rack-temperatures, and values of the rack-cooling index (RCI) were used to compare the cooling characteristics of the two designs. The authors confirm that ceiling supply design is more robust regarding changes in major design parameters compared to floor supply design.

A Progress Update and History of IBE; Plus Papers of the Year, 2012

I begin this editorial by introducing to you a talented young lady whom I met when I was attending the ‘‘Healthy Buildings 2012’’ conference held on July 8–12, 2012, in Brisbane, Australia. I was impressed by her quiet confidence and her intellectual assertiveness. She speaks good Cantonese and has a good command of English language. I attended her presentation of her paper on ‘‘Simulation based validation of two CO2-based demand controlled ventilation control logic for multiple-zone VAV system’’ and was impressed by her knowledge and command of her subject. The reason I am introducing her to you in this editorial is that she has been appointed as the Deputy Editor to assist me with the editing of papers for journal publication. Her name is Dr Josephine Lau. She is an Assistant Professor at the Charles W Durham School of Architectural Engineering and Construction, University of Nebraska-Lincoln of the USA. She, like me, was originally from Hong Kong. She was a first class honours graduate and a Master (with distinction) of Building Services Engineering from the Hong Kong Polytechnic University before she went to the USA where she obtained a further Master degree in Mechanical Engineering from Purdue University and a Doctorate degree in Architectural Engineering from Pennsylvania State University where she was also a graduate teaching assistant. She had won many awards for her thesis dissertations in America and for being an outstanding student when she was in Hong Kong. At a relatively young age, she has already established herself internationally. She is a technical committee member of the Environmental Health Committee of ASHRAE and she is an Associate Editor of the Journal of Architectural Engineering. She has published widely and internationally on a wide variety of subjects on Ultraviolet Germicidal Irradiation (UVGI) air cleaners, ventilation, floor supply displacement ventilation, HVAC systems, CFD simulation of temperature and airflow in multi-zones environments, energy efficiency and indoor air quality, in various journals and conference proceedings. I believe her expertise covers about 75% of the subject areas of our journal which has made her an ideal candidate to be the deputy editor. About 90% of papers submitted to our journal are within the subject areas of her interest, knowledge and expertise. I would also like to introduce to you Dr Zhishi Guo. He is from the US EPA Office of Research and Development, National Risk Management Laboratory, Air Pollution Prevention and Control Division (APPCD), Indoor Environment Management Branch (IEMB). He is retiring this year and he has agreed to join the editorial team of the journal as one of the deputy editors to help me with editing of papers. Zhishi does not really need introduction to many of you who know him as one of the leading experts in indoor source characterization of particulate matters, VOCs and SVOCs, modelling of VOC emissions in built environments and indoor air quality simulation. He was responsible for the US EPA simulation tool kit for indoor

The influence of chemical interactions at the human surface on breathing zone levels of reactants and products

Using computational fluid dynamics simulations of an occupant in a ventilated room, we find that breathing zone ozone levels can be substantially lower and ozone reaction products associated with human surfaces (ORPHS) levels considerably higher than room levels. For air exchange rates <3/h, the ratio of the breathing zone to the ozone concentration 1 m from the body (bulk air), r(ozone), ranges from 0.59 to 0.75 for floor or ceiling air supply. ORPHS are enriched in the breathing zone, with concentrations for these conditions ranging from 1.2 to 2.5 greater than bulk air concentrations. At high air exchange rates (>8/h), the breathing zone concentrations approach bulk air concentrations (r(ozone) > 0.9) with a floor supply, whereas large concentration gradients occur between breathing zone and bulk air with a ceiling supply. At these high air exchange rates, ORPHS levels are 1.6-2.0 and 2.9-6.0 times the bulk air concentrations for floor and ceiling supply, respectively. The extent of depletion of ozone or enrichment of ORPHS is large enough that reliance on micro-environmental measurements alone, to assess the intake of ozone or ORPHS, is undesirable. Chemical reactions between ozone and human and clothing surfaces are predicted to significantly reduce ozone concentrations, and increase ozone reaction products associated with human surfaces (ORPHS) concentrations, in the breathing zone, relative to those concentrations in the larger microenvironment of a room. Existing measurements may overestimate ozone exposure and intake in typical indoor environments.

Numerical study on temperature stratification in a room with underfloor air distribution system

In this study, numerical prediction using computational fluid dynamics (CFD) was utilized to investigate air temperature stratification in a room with an underfloor air distribution (UFAD) system. The numerical modeling using CFD computation was validated with physical test in a full size experimental room with an UFAD system. The different supply air conditions and heat loads were discussed. The results show that the effect of three parameters, heat load, supply volume flux and supply air velocity, on room air temperature would be expressed by the length scale of the floor supply jet. When the length scale increased from 0.8 to 1.56 m, the ratio of vertical temperature difference between 2.5 and 0.1 m at the occupied zone to the difference between return and supply air temperature decreased from 0.62 to 0.25. When there was only one local heat source in the room, there was a thermal stratified interface at the occupied zone. The interface height was about 1.42 times the length scale. The results may suggest ways to optimize UFAD design and operation.

C-21 粒状PCMを組み込んだ躯体蓄熱床吹出し空調に関する研究 : その7 夏季冷房時の全蓄熱実証実験

C-21 粒状PCMを組み込んだ躯体蓄熱床吹出し空調に関する研究 : その7 夏季冷房時の全蓄熱実証実験

Energy analysis for workshops with floor–supply displacement ventilation under the U.S. climates

Many studies have shown that floor–supply displacement ventilation systems are better than mixing ventilation systems. The benefits include indoor air quality, thermal comfort and reduced energy use. The energy benefits depend on the climate conditions. This research compared the energy use of a floor–supply displacement ventilation system in a large industrial workshop with that of a mixing ventilation system for five U.S. climate regions. It was found that the energy use and the system performance vary with the locations. The displacement ventilation system may use more fan and boiler energy but less chiller energy than the mixing ventilation system. The total energy used is slightly less with displacement ventilation, although the ventilation rate was increased in order to handle the high cooling loads found in U.S. buildings. Thus, the displacement ventilation system can save some energy in cooling mode. However, displacement ventilation system has a lower capacity of dehumidification. This system alone, thus, is not suggested for use in humid regions.

Study of a floor supply air conditioning system using granular phase change material to augment building mass thermal storage—Heat response in small scale experiments

We have proposed a new floor supply air conditioning system, using phase change material to augment building mass thermal storage. A scale model was constructed for such a system. Granules containing phase change material (PCM), with a phase change temperature of about 20 °C, were made from foamed glass beads and paraffin waxes. Results from measurements simulating an air conditioning schedule in office buildings indicate that 89% of daily cooling load could be stored each night in a system that used a 30 mm thick packed bed of the granular PCM.

Numerical and experimental study of velocity and temperature characteristics in a ventilated enclosure with underfloor ventilation systems

Airflow and temperature distributions in an enclosure with heat sources ventilated by floor supply jets with floor or ceiling air exit vents were investigated using experimental and numerical approaches. These ventilation configurations represent the floor return or the top return underfloor ventilation systems found in real applications. Experiments and numerical simulations were performed on a full-sized environmental chamber. The results reveal that the temperature stratification in the enclosure highly depended on the thermal length scale of the floor supply jets. When the thermal length scale of the supply jet was >>1, temperature stratification was minor for all tested heat densities and air distribution methods. Significant vertical temperature gradients occurred when the jet thermal length scale was <<1. Changes in air distribution methods also became significant for temperature stratification at small supply jet thermal length scales. Temperature stratification also affected the terminal height of the momentum-dominant region of the vertical buoyant supply jets. The applicability of these results to underfloor ventilation design was also discussed. In designing underfloor ventilation systems, supply jet conditions and heat load density have to be considered to avoid thermal discomfort because of excessive temperature stratifications. This study demonstrated, by both numerical simulations and experiments, that thermal length scale can be used as a design indicator to predict thermal stratifications under a floor return and a top return underfloor ventilation setting.

Robustness of Air Distribution in Plenum-Based Ductless Ventilation Systems

This paper introduces a concept of robustness of an air distribution method, which is defined as being capable of meeting the ventilation requirements during varying operational conditions. The robustness performance may be particularly important when the system allows individual control of the supply air parameters. As a preliminary example, plenum–based (ductless) air distribution methods are studied using computational fluid dynamics. Among the four basic air distribution methods in plenum–based systems, it is found that the floor supply and ceiling return system does not always produce the conventional displacement ventilation system performance when the heat sources are not concentrated. The ceiling supply with ceiling return produces the best robustness performance over a wide range of supply velocities.

粒状潜熱蓄熱材を適用した躯体蓄熱床吹出し空調システムに関する研究 : その2 システムのモデル化と空調機負荷の夜間移行効果

A computer simulation program is constructed for the floor supply air conditioning system in which thermal capacity is augmented by latent heat storage compared to the general building structure thermal energy storage. Calculations can reproduce measurements about variations of air temperatures and stored heat with suitable heat transfer coefficients. Calculations which simulate the air conditioning system in office buildings indicate that daily air conditioner load can be completely shifted to the period for thermal energy storage during night when the available enthalpy difference of granules including phase change material (PCM) is 128.5 kJ/kg.

DIE EFFEKTIWITEIT VAN DIE VLOERPRYSSKEMA AS STABILISASIE-MEGANISME IN DIE PRIMêRE BEESVLEISBEDRYF / STABILISATION OF THE PRIMARY BEEF INDUSTRY: EFFECTIVENESS OF THE BEEF FLOOR PRICE

The Meat Board has administered an auction system with a minimum guarantee price (floor price) for beef carcasses since 1956. The floor price functions as a mechanism to purchase carcasses when beef producer prices decline to predetermined low levels. The Meat Board debones and freezes this meat, which is later sold to the trade. The net effect of these purchasing and selling actions on the annual beef producer price was empirically analysed. The net floor price effect, 1970 to 1993. can be described as negative since the magnitude of price-lowering effects due to Meat Board sales of frozen beef was twice that of price-raising effects resulting from floor price purchases and supply control, taking into account the absolute extent of price lowering and raising effects. Relatively large quantities of beef had to be purchased at floor price before significant price increases resulted, but the selling of relatively small quantities of frozen beef was responsible for significant producer price decreases. Suppl...

Patients Respond Enthusiastically to Nutrition Assistant Program

LEARNING OUTCOME: To describe a service program which increases patient satisfaction with foodservice.Patient satisfaction is a key outcome indicator for Healthcare foodservice operations. Measurement of satisfaction with foodservice is complex and is more than a matter of food quality. Attitude of the staff who deliver menus and meals correlates highly with patient satisfaction. Patients’ perception of the attitude, warmth, efficiency, attentiveness, helpfulness, knowledge, and courtesy of staff influences their overall satisfaction with foodservice.To enhance patient satisfaction with nutrition services at this 420-bed acute care facility, an interdisciplinary team was formed. Using continuous quality improvement methods, the team established the mission of the Nutrition Assistant (NA) program, the NA job responsibilities, qualifications, and training process. Interviews were conducted using an established format and NAs were selected and trained. Nutrition Assistants are assigned to specific patient care units and provide all meal-related services to the patients. The NA for a given unit serves all three meals for the day, assists patients with menu selections, places orders for room service via the computerized order entry system. Duties also include daily inventory and replenishing of floor supply. Nutrition Assistants work collaboratively with the nursing staff and the dietitian or dietetic technician assigned to their unit.Patient satisfaction with Nutrition Services staff has risen significantly with the NA program. Nutrition Assistants regularly receive letters of appreciation from patients and their families. The program has demonstrated enhanced service in this era of cost containment.

Indoor airflow and pollutant removal in a room with floor-based task ventilation: Results of additional experiments

A laboratory-based study of the performance of a floor-based task ventilation system designed for use in office buildings has been completed. With the task ventilation system, occupants can adjust the flow rate and direction of air supplied to their work space through floor-mounted supply grilles. Air exits the ventilated space through a ceiling-mounted return grille. To study indoor airflow patterns, the age of air at multiple indoor locations was measured using the tracer gas step-up procedure. To study the intra-room transport of tobacco smoke particles, cigarettes were smoked mechanically in one workstation and particle concentrations were measured at multiple indoor locations. Test variables included supply flow rates, temperatures, supply directions, and internal heat loads. Multiple floor supply units were in operation simultaneously. During all tests, the ventilation system supplied 100% outside air. Our major findings are as follows. (1) Deviations from a uniform age of air, and a uniform particle concentration, were generally less than 30%. (2) With two floor-supply units operating and supply air directed toward the occupant, the age of air in the breathing zone was about 20–40% less than the age of air that would occur in the room if the air was perfectly mixed. (3) With two floor-supply units operating, the air appears to travel from the floor to the ceiling in a piston-like flow pattern. (4) With three floor-supply units operating, a two-zone flow pattern, with a piston-like flow in the lower region of the room and mixing in the upper region, was evident at some operating conditions. (5) A strong ( r 2 = 0.81) correlation was found between the rate of change in the average age of air with height and two factors hypothesized to be determinants of the indoor airflow pattern. (6) Workstations without a cigarette smoking machine and with an operating task ventilation system were not significantly protected from tobacco smoke in an adjacent workstation.