Ventilating Air Conditioning Research Articles

Combined HVAC and Battery Scheduling for Demand Response in a Building

This article will discuss and simulate a demand management algorithm in a building with a battery energy storage system (BESS) and heating ventilation air conditioning (HVAC) scheduling using the model predictive control (MPC). Behind-the-meter energy storage system is used for modifying the load shape and minimizing the demand charge of a building. The thermal mass of the building can also be utilized to store the heat/cool energy and HVAC is scheduled to minimize power consumption during peak times. Initially, this article works with optimizing BESS using MPC and compares the results with those of regular optimization. Later HVAC is modeled mathematically to be able to use in optimization. Finally, this article will co-optimize the battery and HVAC schedule minimizing the annual electricity bill without causing thermal discomfort to the residents of the building. The platform has been simulated on a sample building modeled in EnergyPlus.

Distributed iterative learning temperature control for multi-zone HVAC system

By taking the dynamic features of the multi-zone heating ventilation air conditioning (HVAC) system into consideration, a distributed iterative learning temperature control (DILTC) method is proposed for building rooms where the exact values of the thermal capacitances, as the key parameters of the HVAC system, are unavailable. At first, an iterative dynamic linearization is applied to reformulate the HVAC system into an all-purposed linear incremental form virtually to facilitate the controller design without relying on model information. On this basis, a data-driven DILTC method is proposed with rigorous convergence analysis where the topology among rooms is considered via a thermal resistance matrix. Under the developed convergence conditions, the tracking error is guaranteed to be iteratively decreased to a small bound with nonrepetitive disturbances. If the disturbances are completely repeatable, a perfect tracking performance can be achieved. The results have also been extended to the HVAC systems subjected to I/O constraints to address the limited heating and cooling capacities. Through extensive simulations, we confirm the good efficiency and applicability of the proposed methods.

Building Management System

A Building Management System is also known as Building Automation System (BAS), It is a Computer based control system installed in buildings that controls and monitors buildings mechanical and electrical equipment such as ventilation, lighting, power systems and security systems. A building management system for METRO includes inputs from the systems like HVAC (Heating Ventilation Air Conditioning), Lifts Escalators, UPS and Fire Alarm and Detection System etc. A Building Management system uses a PLC controller along with SCADA suite to monitor and control all the systems included in the Metro. BMS provides Automatic Fault Detection System and diagnosis strategies for building energy performance.

Simulation of a controlled water heating system with demand response remunerated on imbalance market pricing

Buildings are responsible for 40% of our worldwide energy consumption and 50% of this energy is converted for Heating Ventilation Air Conditioning (HVAC) systems in buildings. The increasing share of renewable energy production required to make the transition towards a carbon neutral energy system challenges the stability of the grid. Through demand response it becomes possible to activate these systems in support of grid balancing. However, this flexibility is currently not rewarded in the market. We simulate a domestic water heater participating in the balancing of the electricity net and calculated the revenue from this action. We simulate a water heater in connection with an Economic Model Predictive Controller (EMPC) which takes future usage, energy cost, and reward for delivering balanced power into account. We show that the choice of an EMPC controller is valid as it allows the setpoint to change if certain conditions are met, leading to a more optimal revenue stream from selling flexibility. We find that the economic benefits of participating in delivering balancing power is considerable and offset an increase in energy costs. The increase in energy consumption could be justified as the participation in net stabilisation allows the macro-system to integrate more renewable energy sources. More importantly, the simulations also show that the poorer the energy performance of the water heater, the more flexibility can be sold. From a policy point of view, a minimal energy performance should be determined before allowing participation in net stabilisation.

Case study assessment for natural ventilation performance of heritage buildings in the Mediterranean city of Alexandria (Egypt)

Historic buildings are an important aspect of any city in their capacity to provide cultural reference points. Demonstrating capacity for better levels of energy efficiency and thermal comfort has become a critical challenge to such buildings’ survival. Wind driven natural ventilation in buildings is one way of reducing energy use by dependence on mechanical ventilation. This paper is a case study assessment of a nineteenth-century listed residential building located in the historic business district of the Mediterranean city of Alexandria (Egypt). From an architectural perspective, the European style courtyarded building offers good potential for healthy indoor air replacement, and the Mediterranean climate of the city provides enhanced possibilities for promoting indoor thermal comfort. Yet observation of the building today demonstrates that occupants rely heavily on mechanical ventilation (air conditioning) . It is clear that the building’s original layout has been modified. In this research, we use 3D RANS CFD simulation to investigate the potential for the original layout of the building to enable natural air flow patterns. Simulations are validated against air speed measurements in parts of the building. The results show a detailed natural ventilation deficiency performance in the case study building as modified today, and indicate potential for future improvement. This investigation can help in the understanding of conservation approaches that not only preserve the building’s cultural value but also reclaim its natural ventilation performance.

Improving the Energy Efficiency, Limiting Costs and Reducing CO2 Emissions of a Museum Using Geothermal Energy and Energy Management Policies

Museums are major energy consumers amongst buildings, especially if they are housed in historical constructions. Museums usually present high energy demand for the air-conditioning due to their architectonical and structural characteristics, such as the presence of large exhibition rooms and open spaces. At the same time, temperature and humidity have to be strictly controlled in order to assure proper microclimate conditions for the conservation of the housed collections and adequate thermal comfort for visitors and personnel. Moreover, despite being subjected to architectural protection that limits most structural refurbishment interventions, these buildings must be adequate from an energy point of view to allow their reuse or continuity of use according to current quality standards, while retaining their heritage significance. In this awkward context, ground source heat pump working with high temperature terminals is proposed as a viable refurbishment solution. The use of shallow geothermal systems can improve the energy efficiency of the heating ventilation air-conditioning systems and, at the same time, increases the renewable energy source exploitation without affecting the indoor environmental conditions. However, after the interventions, the expected benefits and the sought-after limitation of energy consumption/cost may not occur for different reasons. In fact, even if the installed solution is working perfectly and properly designed, every effort will be in vain if adequate attention is not paid to the management of the plants during the operational phase. This document is meant to evaluate and compare the magnitude that invasive (i.e., technical interventions) and not invasive (i.e., energy management policies) actions respectively and their combined interaction, have on a museum. Through energy simulations it has been possible to quantify the effects that different interventions and energy management strategies had on an existing museum housed in an historical building, from energy consumption, energy costs and CO2 emission standpoints.

Optimization and Evaluation of Ventilation Mode in Marine Data Center Based on AHP-Entropy Weight.

The ventilation mode affects the cooling efficiency of the air conditioners significantly in marine data centers. Three different ventilation modes, namely, underfloor ventilation, overhead ventilation, side ventilation, are numerically investigated for a typical marine data center. Four independent parameters, including temperature, velocity, air age, and uniformity index, are applied to evaluate the performances of the three ventilation modes. Further, the analytic hierarchy process (AHP) entropy weight model is established and further analysis is conducted to find the optimal ventilation mode of the marine data center. The results indicate that the underfloor ventilation mode has the best performance in the airflow patterns and temperature distribution evaluation projects, with the highest scores of 91.84 and 90.60. If low energy consumption is required, it is recommended to select the overhead ventilation mode with a maximum score of 93.50. The current evaluation results agree fairly well with the three dimensional simulation results, which further proves that the AHP entropy weight method is reasonable and has a high adaptability for the evaluation of air conditioning ventilation modes.

Statistical analysis using taguchi method for wind turbine in ducting system

Wind turbine is a device that converts kinetic energy of wind into electrical energy. Weak air pressure with an average of 2m/s to 4m/s makes wind turbine implementation in Malaysia becoming difficult and unrealistic. In order to produce a good power and torque, a quality air pressure is needed. Wind turbine performance depends on the incoming wind speed. Fluctuating and low quality air pressure are the significant challenges in wind turbine implementation. There are many types of mechanism and control but the production of output power is still considered low compared to the actual equipment. In a large building, Heat Ventilation Air Conditioning (HVAC) system is highly required to control the indoor temperature and consistent air pressure through ducting. The consistency of air pressure in ducting system make a drive for this research to proposed a wind turbine implementation in ducting system in order to produce electrical energy. In HVAC there are five parameters to be considered in order to identify the air pressure distribution in ducting system. These five parameters are input air pressure, ducting height, distance between blower to the pipe, total effective length and gap between trunk or run out. In this paper, an analysis of air pressure effect in a ducting system will be conducted via a development of air pressure prototype. Thousands of experiments are required with regards to a huge number of experiments to be considered. Spesifically a statistical analysis Taguchi Method is used to reduce a number of experiments. Without statistical analysis, 3125 experiments shall be conducted to identify the air pressure distribution in the ducting system. However, these huge number of experiments are reduced to only 25 experiment by using Taguchi method based on the function of L25 in array orthogonal

Water evaporation rate of RSG-GAS spent fuel storage pool

Water in spent fuel storage pool that serves as a water cooling of decay heat and radiation shielding must be kept steady from evaporation. Knowledge of the evaporation rate of spent fuel storage pool is needed so that the amount of make up water can be well known for nuclear safety purposes. This study aims to calculate the rate of water evaporation in RSG-GAS spent fuel storage pool. The Shah and Carrier correlations were used to calculate the rate of evaporation based on operational data obtained in the spent fuel storage pool, i.e, pond water temperature, room temperature, relative humidity, and airflow velocity in the SFSP building. The evaporation rate calculation was performed in two conditions: during ventilation and air conditioning are operated and not operated. The calculation result shows that the rate of water evaporation rises from 0.0138 kg / m2.h to 0.0747 kg / m2.h when using Shah correlation, and from 0.0153 kg / m2.h to 0.0831 kg / m2.h when using Carrier correlation. From the calculation found that the needs of make-up water per day to replace the water loss by evaporation is 42.28 - 43.84 kg / day. The rate of evaporation of pond water during operational of ventilation air conditioning is greater than when ventilation air conditioning is not operated. The result shows that the increase of water evaporation rate of spent fuel storage pool is strongly influenced by the increase of vapor pressure difference and the length of operation time of VAC.

Improve the HVAC contribution in wind power smoothing

Energy produced by wind turbines is characterized by its uncertainty which causes high fluctuations. Two types of fluctuations exist: the first one is represented by the slow power variation measured during large period; the second is the fast power variation measured from minute to minute that is known by the ramping rate. In this paper, the second type is studied. The high level of penetration of these fluctuations may affect the power network quality and may cause voltage and frequency instability. Power smoothing that is defined in this paper by ramping rate control is an important issue to avoid these fluctuations and to maintain the power network stability. Conventional methods based on storage system and on delta control of wind turbines are published in literature for this purpose. Unfortunately, storage systems are either small or expensive and delta control reduces yield energy. Another approach consists of adding to the delta control the power consumption control of heating and ventilation air conditioning (HVAC) systems installed in large buildings. This would provide positive and negative electrical power reserve for the compensation of wind power fluctuations. Unfortunately, this technique is still limited by a small margin of control since neither the temperature nor the humidity of the air-conditioned zones should be affected. This paper suggests an improvement of this margin of control by integrating in the regulation process the supply fan with the return fan. A numerical study based on real data shows that the proposed method is more advantageous than using slow response heat storage systems or expensive storage batteries or DC controllers. Moreover, this method reduces wind power losses and keeps the temperature variation unperceived, although an important reduction in electrical power fluctuation is achieved.

Transactive control of industrial heating–ventilation–air-conditioning units in cold-storage warehouses for demand response

Abstract This paper establishes a transactive coordination model of heating–ventilation–air-conditioning (HVAC) loads for demand response purpose. The thermal inertia of industrial thermostatically controlled loads may provide verities of ancillary service in the power system by adjusting their temperature set-points. The HVAC aggregator bids temperature set-points to minimize opportunity cost subject to crucial operational constraints. The cost due to changing temperature set-point from reference is captured by a piece-wise linear function. A dual decomposition based distributed optimization framework is used to optimize the coolant flow rate in the facility for a given temperature set-point. By optimizing temperature set-point and coolant flow, the HVAC system can modify the electrical power consumption at peak hours. The effectiveness of the model is verified by simulating several plausible cases. It is found that overall energy consumption cost significantly reduces; drop the electricity prices while having little effect on the operation of the cold-storage plants.

A comprehensive review on the application of artificial neural networks in building energy analysis

This paper presents a comprehensive review of the significant studies exploited Artificial Neural Networks (ANNs) in BEA (Building Energy Analysis). To achieve a full coverage of the relevant studies to the scope of the research, a three-decade time span of the publishing date of the existing studies was taken into account. The review focuses on the studies utilized ANN to analyze the energy-related issues associated with buildings in major areas, including modeling of water heating and cooling systems, heating and cooling loads prediction, modeling heating ventilation air conditioning systems, indoor air temperature prediction, and building energy consumption prediction. Moreover, the findings of the abundant reviewed studies along with the potential future research to be carried out are discussed elaborately. Regarding the comprehensive review conducted, it is found out that the majority of studies focused on building energy consumption and indoor air temperature prediction. Additionally, it is observed that there has been a growing interest in the application of newly-developed ANNs to BEA areas, such as general regression neural network and recurrent neural network, due to their abilities in improving the modeling and prediction of buildings energy analysis. It is believed that this thorough review paper is useful for the researchers and scientific engineers working on the application of AI-based techniques to the building-energy-related areas to find out the relevant references and current state of the field.

Control Strategies in Multi-Zone Air Conditioning Systems

In a commercial building, a significant amount of energy is used by the ventilation systems to condition the air for the indoor environments to satisfy the required quantity (temperature and humidity) and quality (amount of fresh air). For many years, Variable Air Volume (VAV) systems have been considered as the most efficient solutions by balancing the airflow volume based on the demand making them energy efficient when compared with the traditional Constant Air Volume (CAV) systems. However, the setpoints in VAV systems are often misread by the sensors due to stratification and formation of pollutant pockets and responding to design levels that overestimate the real-time demand conditions, which result in waste of energy, thermal discomfort and unhealthy air. In general, VAV devices are expensive, complicated and prone to failures and they are used only in medium and large projects. More recently, new technologies have evolved to solve this issue. In one of the new solutions, VAV motors terminals are replaced with flaps which are simpler and less expensive thus, they can be implemented in a wider range of projects. In systems, balancing and supplying the optimal airflow to reduce the energy consumption while delivering ideal thermal and Indoor Air Quality (IAQ) levels are the main challenges. In this paper, a comparison of the recent technologies with traditional VAV systems is presented to be used as a guild line for researchers and designers in the field of Heating Ventilation Air Conditioning (HVAC).

The effects of indoor and outdoor air pollutants on workers’ productivity in office building

In the present-day society, people spend about 80% of their time inside buildings, and specifically 30-40% in workplaces. From this evidence, the indoor environmental quality needs to be investigated, and in particular, the possible sources of indoor-outdoor pollutants and their impact on the human health, comfort and productivity. First, through an examination of the indoor sources of pollution, the research analysed the main substances that affect indoor air quality in an office. Second, the pollution of external origin and its effects on the performance of employees were taken into consideration. Two scenarios were designed for a Heating Ventilation Air Conditioning (HVAC) system in an office building; one by the installation of a biocidal filter and the other by a traditional one. Two methods were applied to evaluate and compare those scenarios; the Cost Benefit Analysis and the Monte Carlo Simulation. From a financial point of view, the investment and management costs of the filters were considered. Instead, the annual benefits included increasing productivity and reducing days of absence from work due to illness. The results confirmed the energy and socio-economic efficiency of the antibacterial filter; it can be considered a solution to achieve the best income.

Verification of the effect of sleeping environment and humidification on middle-aged people in whole-house air-conditioning ventilation system housing

This study focused on the thermal comfort of air circulation-type whole-house air-conditioning ventilation systems. We studied the influence of 24-h continuous whole-house air-conditioning on the living environment in which the occupant is sleeping. A survey was conducted in the summer of 2016 and winter of 2017 to ascertain the influence on the sleeping environment, skin moisture content, and blood pressure. We then compared the results with those of the sleeping environment of residents in air-conditioned housing surveyed the previous year. The sleeping environment when using a personal humidifier around the occupant’s head was examined during winter when the humidity is low. The results indicated that sleep latency was significantly shortened in the 24-h continuous whole-house air-conditioning ventilation system in both summer and winter because the temperature control of the bedroom before going to bed affects the sleep latency. Subjectively, no participants felt dryer than the values measured in the bedroom environment. The results implied that the comfort of the entire building was improved with continuous air-conditioned housing.

Analysis of the Methodologic Assumptions of the NOM-020-ENER-2011—Mexican Residential Building Standard

In Mexico, residents of low income housing mainly achieve thermal comfort through mechanical ventilation and electrical air conditioning systems. Though government and private efforts have risen to meet an increasing demand for social housing, the average construction quality and thermal comfort of new housing stock has decreased over the years. Various programs and regulations have been implemented to address these concerns, including the 2011 residential building standard NOM-020-ENER-2011. This standard attempts to limit heat gains in residential buildings, in order to reduce the energy consumption required from cooling systems, and was intended to be applied throughout Mexico. NOM-020-ENER-2011, however, divides the country into just four climatic zones and only considers the energy use of cooling systems, disregarding heating costs. The recommendations of this policy are thus inadequate for the many regions in Mexico that have mild to moderate winters. This study discusses the assumptions and calculations that underlie NOM-020-ENER-2011, identifying several problems and recommending specific changes to the standard that would lead to greater comfort and lower energy use throughout Mexico.

Numerical Studies on Heat Ventilation Air Conditioning (HVAC) System in Operation Theaters: a Review

The current review compiles and analyzes the literature on Computational Fluid Dynamics (CFD) studies related to Heat Ventilation and Air conditioning (HVAC) in Operation Theaters (OT). The paper describes the various types of ventilation systems, used in Operation Room (OR) to maintain the Indoor Air Quality (IAQ). The numerical studies show the effect of the HVAC system in contamination dispersion, temperature distribution and airflow patterns. Numerous researchers have worked considering various aspects such as the thermal comfort of the patient and staff, effect of heat due to lighting equipment and the resultant effect on the contamination flow pattern. The most common issue reported throughout the literature being, the contamination sources and their flow behavior.

Calibrated simulation analysis for integration of evaporative cooling and radiant cooling system for different Indian climatic zones

Radiant cooling system (RCS) has proven to be an energy efficient system for meeting a building's cooling requirements. RCS is energy efficient and provides better thermal comfort compared to conventional all-air heating ventilation air conditioning (HVAC) system. To further improve the efficiency of RCS, a parallel evaporative cooling system (cooling tower) is coupled with RCS and analyzed for different climatic condition using calibrated model. A statistical analysis of weather files (based on wet bulb temperature), was used to identify the availability of useful water for cooling tower integration with RCS. A comprehensive simulation feasibility study of the application of cooling tower in RCS was performed for different cities to cover every climatic zones of India. It was found that in summer, the wet bulb temperature (WBT) of different climatic zones, except warm-humid, is suitable for the integration of cooling tower with RCS. An experimental setup was designed and developed for integration of parallel chiller and cooling tower with panel-based RCS for cooling and a dedicated outdoor air system (DOAS) for dehumidification and ventilation. Experiments were conducted for chiller and cooling tower operated RCS in Composite climate of Jaipur, Rajasthan, India. Building Energy Models (BEM) were developed for both the chiller-operated RCS and cooling tower-operated RCS in EnergyPlus and calibrated with the measured data. Using the calibrated models, performance of the system was analyzed for different climatic zones of India. A chiller-operated RCS was considered as a baseline to compare the annual energy saving potential and monthly performance of the cooling tower integrated RCS. In the cooling tower–operated RCS, a total annual savings of 7% in hot and dry climates, 11% in composite climates and 20% in temperate climates was achieved compared to the chiller-operated RCS.

Experimental Study of Heat Pipe Heat Exchanger Multi Fin for Energy Efficiency Effort in Operating Room Air System

This study was conduct to identify the effectiveness and heat recovery values of heat pipe heat exchangers (HPHEs) in heating ventilating air conditioning (HVAC) ducting systems. HPHEs are passive modules which provide the energy recovery function in

Study of an integrated personalized ventilation and local fan-induced active chilled beam air conditioning system in hot and humid climate

A novel integrated personalized ventilation and local fan-induced active chilled beam (PV-ACB) air conditioning system is proposed and analyzed through energy and Computational Fluid Dynamics (CFD) simulation methods. Energy performance and indoor environmental conditions of this system are investigated via Integrated Environmental Solutions (IES) and ANSYS Fluent respectively. Energy simulation results illustrate that PV-ACB system, compared with the conventional variable air volume (VAV) system, could achieve 16% energy savings at 100% peak cooling load. A maximum 42% energy savings is obtained at 25% part cooling load, indicating the superior energy saving potential under part load conditions. Vertical thermal stratification is observed in CFD simulation results, 23–24 °C at the occupant level (0–2 m) and 26–27 °C in the upper zone (2–4 m). Horizontally, temperature around occupants is 22–23 °C, lower than the temperature of 26–27 °C in other areas, demonstrating the horizontal temperature difference caused by the conditioned outdoor air from personalized ventilation. Both energy and CFD simulation results illustrate that this novel PV-ACB air conditioning system is able to achieve considerable energy savings, superior occupant thermal comfort and enhanced indoor air quality (IAQ).