Heating Ventilation Air Conditioning System Research Articles

Geothermal heat pumps for sustainable farm climatization and field irrigation

In intensive breeding farms, maintaining an adequate indoor thermal environment and air quality is crucial in order to establish healthy conditions and increase productivity. In the EU, fossil fuels and electricity are the main energy sources adopted for this purpose, yet introducing renewable energy sources and efficient Heating Ventilating Air Conditioning systems would reduce energy consumption and improve sustainability.Another environmental concern in agricultural production is related to the intensive use of fertilizers, causing nitrate contamination in surface water and groundwater. Therefore, innovative strategies to reduce fertilizers and simultaneously reduce primary energy consumption are worthy of investigation.This paper addresses both issues, studying the application of geothermal heat pumps in the agro-zootechnical sector, where they are rarely applied and thus their potential needs to be verified. The study considers systems based on the closed loop configuration, i.e. Ground Source Heat Pumps (GSHP), and on the open loop configuration, i.e. Groundwater Heat Pumps (GWHP).Firstly, a pilot GSHP system for a piglet stable in Northern Italy is presented. Thanks to the use of both ground source and thermal recovery of air ventilation, the system achieves an appreciable reduction in both primary energy consumption and running costs, compared with a more traditional system typically adopted in this kind of farm.Secondly, the feasibility of an innovative concept of a GWHP combined with the irrigation system is studied through numerical modelling. The area of the piglet stable is represented in a flow and heat transport model; groundwater used by the heat pump is re-injected up-gradient during the cold season, while it is used for irrigation during the warm season. The system would provide energy-efficient climatization to the farm stables and, at the same time, promote the reuse of nitrogen in cultivated fields as a result of groundwater recirculation through irrigation.

Parametric Investigation Using Computational Fluid Dynamics of the HVAC Air Distribution in a Railway Vehicle for Representative Weather and Operating Conditions

A computational fluid dynamics (CFD) analysis of air distribution in a representative railway vehicle equipped with a heating, ventilation, air conditioning (HVAC) system is presented in this paper. Air distribution in the passenger’s compartment is a very important factor to regulate temperature and air velocity in order to achieve thermal comfort. A complete CFD model, including the car’s geometry in detail, the passengers, the luminaires, and other the important features related to the HVAC system (air supply inlets, exhaust outlets, convectors, etc.) are developed to investigate eight different typical scenarios for Northern Europe climate conditions. The results, analyzed and discussed in terms of temperature and velocity fields in different sections of the tram, and also in terms of volumetric parameters representative of the whole tram volume, show an adequate behavior from the passengers’ comfort point of view, especially for summer climate conditions.

Comparative Study of Cost and Power Consumption of HVAC System Using Phase Change Material

Phase change materials (PCM) are materials which absorb the latent heat of the surrounding air. They usually have characteristics such as near to constant temperature operating range with high energy density of melting from solidified state. Nowadays, heating ventilation & air conditioning (HVAC) of commercial & domestic buildings, green rooms in pharmaceutical companies is necessary for maintaining desired atmospheric condition inside the building compound for optimum working environment. For doing so, lot of energy is consumed in this process. Therefore, there is a need of reduction in power consumption where PCM finds a huge market. These materials store the latent heat of the net heat available as latent heat thermal energy without increase in its temperature. Thus, there is a large scope for its usage for reducing the heat load for refrigerating effect for a specified area. This paper intends to compare the variation in heat load calculation of air refrigerated areas like that in commercial buildings, domestic purposes, industrial applications etc. with and without the use of PCM materials.

Draught Comfort in a Slot-ventilated Room at various Inlet Aspect Ratios

Slot-ventilated rooms are widely used in comfort type HVAC (Heating, Ventilation, Air Conditioning) systems, where the air inlet is usually a simple slot-diffuser. The geometry of the slot is often expressed by the aspect ratio (AR), which is an important designing parameter of the room air distribution in ventilation systems. Aspect ratio of the slot-diffuser is the non-dimensional ratio of the slot's length and width. This AR value can influence room airflow characteristics, including draught comfort. Previously, the effect of inlet aspect ratio on a slot-ventilated room's draught environment was not investigated. In this article, the influence of various aspect ratios was investigated on a slot-ventilated model room's draught comfort, using Fanger's DR model. The investigations included air velocity and temperature measurements in a full-scale single (or cellular) office model room and the measured data were evaluated with statistical methods.

Ancillary Services Through Demand Scheduling and Control of Commercial Buildings

Prior work showed building Heating, Ventilation, Air Conditioning (HVAC) systems can provide ancillary services to the power grid without sacrificing occupant comfort if the reference power variation is of high frequency (seconds to a few minutes). This paper addresses the question of how to do that when the reference power variation is of lower frequency, e.g., periods of a few minutes to an hour. The proposed control system to do so uses a two-layer architecture. An optimizer schedules the baseline cooling and heating power of a building based on load forecasts. A lower level controller is then used to track the scheduled baseline plus ancillary service reference signal. The schedule is periodically updated based on indoor measurements to ensure quality of service in spite of load forecasting error. The algorithm is tested in simulation. Results show that ancillary services in the frequency range of $f \in {[1/(1\; \text{hour}),1/(10\; \text{minutes})]}$ can be extracted from commercial building HVAC systems while still maintaining a comfortable indoor climate.

Study on the Energy Efficiency Optimization of Solar Power System

In this paper, we design solar power controller based on the model in which the HVAC(Heating, Ventilation, Air Conditioning) fan driving type and hybrid charging type are combined to optimize the energy efficiency of eco-friendly solar cell-based vehicle HVAC system. Because the system characteristics of the traditional MPPT method have many limitations to be applied in vehicle with relation to driving the HVAC blower motor, the limitations and efficiency of such pre-existing system was improved through designing the MPPT load variation method that is able to be used with the MCU(Micro Controller Unit) and is altered from the MPPT P&O(Perturbation and Observation). The DC step down converter(Buck) was used, which allowed for the efficiency to be increased by at least 10% when applied in the HVAC blower motor. And the system was designed to allow the battery to be charged by using the DC-DC step up converter(Boost). In order to confirm the efficiency of the proposed controller system, the results from conducting the operating experiment and vehicle performance evaluation verified the system efficiency.

A newly composed paraffin encapsulated prototype roof structure for efficient thermal management in hot climate

For efficient thermal management in the building under hot weather condition a new paraffin composition as suitable PCM is needed. Several notable attributes of paraffin wax including thermo-physical properties, open air atmospheric condition, economy, and environmental amiability make them suitable PCM for incorporation in the building. Thus, new PCM with massive storage of heat or cold in a specific volume is demanded. Iraqi local paraffin waxes as PCM are proven to be highly prospective due to their high-vitality thickness and isothermal conduct. However, thermal performance optimization of new PCM is pre-requisite to determine its effectiveness in hot climate location. We prepare three new PCM compositions with different oil to wax ratios from the crude petrochemical feed stock waste using fractionation followed by de-waxing and crystallization. The melting temperatures and flash points of these paraffin waxes are ranged between 19 and 44 °C and 177–256 °C, respectively, which upon encapsulation in the prototype roof construction are demonstrated to produce thermal comfort in rooms under hot climate (Iraq). Furthermore, these indigenous PCMs (local paraffin) are abundant, environmental friendly, economic and save electricity cost and HVAC (heating-ventilating air conditioning) systems. Experimental results displayed much reduced temperature fluctuation and internal heat flux of the prototype room than the commercial PCMs. Temperature profiles and solar irradiances inside the room on hot summer days in Bagdad showed remarkable electricity saving. This newly extracted PCM being non-flammable and thermally comfortable are truly secure for buildings construction worldwide.

Economic MPC of Aggregating Commercial Buildings for Providing Flexible Power Reserve

In order to increase the utilization of renewable energy sources and to reduce the need of generator-provided ancillary services and inefficient peaking generation, buildings are progressively transforming into smarter electricity consumers and active participants in power system operations. In this work, an R-C thermodynamic model of building that strongly relates to the power consumption of heating ventilation air-conditioning system (HVAC) is firstly introduced. To offer the aggregated flexible HVAC power to the grid as regulating power, we propose a building-aggregator-grid contract framework and formulate a robust model predictive control (MPC) algorithm which both maximizes the profit of aggregator and minimizes the payment of each participating building to optimally declare power flexibility. Lastly, simulation results on a group of real and hypothetical buildings validate the feasibility of the proposed method.

Design and experimental analysis of an efficient HVAC (heating, ventilation, air-conditioning) system on an electric bus with dynamic on-road wireless charging

The design, control and experimental verification of an HVAC (heating, ventilation, air-conditioning) system to achieve high operational efficiency for an electric bus equipped with a dynamic wireless charging capability are described in this paper. Target power capacities of the HVAC system have been set as 28 kW of cooling and 26 kW of heating with a 600 V in-vehicle environment with COPs (coefficient of performance) of more than 1.6 for cooling and 2.6 for heating, which are required for customer's comfort. For an efficient HVAC system design, an integrated air-conditioning with a heat pump system is proposed and analyzed to meet the objectives of the HVAC system, incorporating the waste heat recovery from the drive motor, its driver, and other wireless charging electric modules. In addition, a control algorithm for operational energy management, considering the real-time power consumption and the wirelessly delivered power, is also proposed and verified to secure an actual operational energy consumption target. Through the component- and vehicle-level of the experimental performance verification, combined with energy demand dynamic model, the proposed HVAC system is verified experimentally to meet target power capacities and efficiency measures for cooling and heating, which are important to electric buses, especially with dynamic wireless charging capability.

Distributed Energy Consumption Control via Real-Time Pricing Feedback in Smart Grid

This brief proposes a pricing-based energy control strategy to remove the peak load for smart grid. According to the price, energy consumers control their energy consumption to make a tradeoff between the electricity cost and the load curtailment cost. The consumers are interactive with each other because of pricing based on the total load. We formulate the interactions among the consumers into a noncooperative game and give a sufficient condition to ensure a unique equilibrium in the game. We develop a distributed energy control algorithm and provide a sufficient convergence condition of the algorithm. The energy control algorithm starts at the beginning of each time slot, e.g., 15 min. Finally, the energy control strategy is applied to control the energy consumption of the consumers with heating ventilation air conditioning systems. The numerical results show that the energy control strategy is effective in removing the peak load and matching supply with demand, and the energy control algorithm can converge to the equilibrium.

Linear algebra solution to psychometric analysis of air-conditioning systems

The typical air conditioning steady-state processes are graphically represented by straight or curve lines on the psychrometric chart. Neglecting the sensible heat of the moisture results in decoupling the sensible and the latent heat, that results in linear variation of the enthalpy on the psychrometric chart. The vapor saturation curve may also be linearized by using Newton's method. If the mass flow rates of the dry air are known and if the computational causality is assigned to correspond to the physical causality (i.e. if a direct modeling problem is treated), then the steady-state models of the psychrometric processes become linear algebraic equations in the vector space defined by the dry bulb temperature and the humidity ratio. Coupling these models to describe a complex HVAC (heating ventilation air-conditioning) system results in a system of linear equations that solves a direct (or psychometric analysis) problem in which the inputs of the model are a subset of the set of independent variables of the psychical process, the outputs of the model are a subset of the set of the dependent variables of the physical process, and the unknowns are the psychometric states of the moist air. The algorithm that implements this method represents a computational alternative to graphical representations and manual solutions to psychometric analysis of air-conditioning systems.

System Design for Energy Efficiency Optimization of HVAC System

In this study, the HVAC(Heating, Ventilation, Air Conditioning) system is designed based on the model in which the HVAC fan driving type and hybrid charging type are combined together to optimize the energy efficiency of the HVAC system by applying eco-friendly photovoltaic power generation. The efficiency increased by approximately 10% when the DC step down converter, also known as a buck converter that has a circuit with the input and output sharing the same ground, was used and applied in the HVAC blower motor. At the same time, the system was also designed to supply electric power as an auxiliary power source to the alternator and to charge the battery as a boost by making use of the LTC3814-5, which is a chip exclusively for the DC-DC step up converters. In order to confirm the efficiency of the proposed system, operating experiment and vehicle performance evaluation were conducted.

Smart HVAC System Control using RF and Zigbees

Many a times the industrial HVAC (Heating Ventilation Air Conditioning) systems do not rely on occupancy. Even if the number of occupants is less it continues to run thus consuming huge amounts of power. Real-time occupancy information can potentially be used to reduce energy consumption. The paper proposes an Arduino based dynamically controlled system which takes occupancy into account and then produces an optimum power solution. The proposed solution can track real-time location of tagged occupants, and report the occupancy at zone level. Using efficient power control mechanisms the efficiency of detection can be maximized and then an optimum solution for power consumption can be determined. Simple ID’s to the RF/Zigbees tags are assigned so that it can be used to track people around a room and report real time occupancy. Then using Gobetwino [1] the details are logged which are then sent to the central server and the exact occupancy is determined. To determine the exact location, Matlab is used to solve optimization equations. Now it has been observed that a person working in an organization has a fixed seat or it has only some minor variations. So using the proposed optimization algorithm it can determine whether that the person will sit in a particular location and then it optimizes the power requirement. So this will help in determining the optimum solution for that person and based on that the power will be delivered to that particular location. The system has been designed as a module so that it can be repeated and scaled to any level. Though at the beginning the system(machine learning algorithm) takes time to find the equilibrium for a particular tag but once it establishes equilibrium it holds on to it and optimizes the power requirement. This paper aims to achieve the solution to the occupancy and optimization problem through a simple Arduino solution. General Terms Optimization, RF Tags, Zigbees, SQL Database, Gobetwino

계시별 전기 요금제하의 에너지 절약을 위한 건물 냉방 제어 방법의 개발

The commercial buildings are consuming about 30% of total energy used in Korea. And a large amount of energy consumption in commercial buildings is consumed by HVAC(Heating, Ventilation, Air Conditioning) system. Therefore, if we can reduce the energy consumption in HVAC or air-conditioning system in commercial buildings, the overall energy consumption in Korea can be reduced. Currently, an electricity charge called Time of Use (TOU) is applied to typical commercial buildings. This paper proposes the novel energy management method where the temperature setting of air-conditioning system are adjusted to minimize the use of electrical energy while indoor comfort level is retained. The simulation test for a typical commercial building shows that the proposed method gives over 10% savings in electricity bills and electricity consumption compared to the conventional air-conditioning method.

Importance of occupancy information for building climate control

This paper investigates the potential of using occupancy information to realize a more energy efficient building climate control. The study focuses on Swiss office buildings equipped with Integrated Room Automation (IRA), i.e. the integrated control of Heating, Ventilation, Air Conditioning (HVAC) as well as lighting and blind positioning of a building zone or room. To evaluate the energy savings potential, different types of occupancy information are used in a Model Predictive Control (MPC) framework, which is well-suited for this study due to its ability to readily include occupancy information in the control.An MPC controller, which controls the building based on a standard fixed occupancy schedule, is used as a benchmark. The energy use of this benchmark is compared with three other control strategies: first, the same MPC controller which uses the same schedule for control as the benchmark, but turns off the lighting in case of (an instantaneous measurement of) vacancy; second, the same MPC controller which uses the same schedule as the benchmark for control, but turns off lighting and ventilation in case of (an instantaneous measurement of) vacancy; and third, the same MPC controller as the benchmark but using a perfect prediction about the upcoming occupancy.This comparison is carried out for different buildings, HVAC systems, seasons and occupancy patterns in order to determine their influence on the energy savings potential.

Image processing analysis of vortex dynamics of lobed jets from three-dimensional diffusers

The passive control of jet flows with the aim to enhance mixing and entrainment is of wide practical interest. Our purpose here is to develop new air diffusers for heating ventilating air conditioning systems by using lobed geometry nozzles, in order to ameliorate the users’ thermal comfort. Two turbulent six-lobed air jets, issued from a lobed tubular nozzle and an innovative hemispherical lobed nozzle, were studied experimentally. It was shown that the proposed innovative concept of a lobed jet, which can be easily integrated in air diffusion devices, is very efficient regarding induction capability. A vortical dynamics analysis for the two jets is performed using a new method of image processing, namely dynamic mode decomposition. A validation of this method is also proposed suggesting that the dynamical mode decomposition (DMD) image processing method succeeds in capturing the most dominant frequencies of the flow dynamics, which in our case are related to the quite special dynamics of the Kelvin–Helmholtz vortices.

Energy efficient building services for tempering performance-oriented interior spaces – A literature review

The main focus of this paper is a literature review of analyses of high performance indoor environments which aid in the design of appropriate energy efficient Heating-Ventilation Air Conditioning (HVAC) systems. In the past, investors planned and built interiors primarily according to economic considerations. Aspects of performance-oriented interior spaces were not taken into account. Yet, to meet growing expectations and requirements, it is necessary to combine thermal comfort features and energy efficient HVAC systems. A huge amount of electricity is necessary for the operation of these systems. Overall, one-third of the final energy is consumed by the provision of space heating and hot water in Germany. More than 95% of this demand is met through the use of fossil fuel. There is, however, a great potential to reduce CO 2 emissions. Forward-thinking planning includes both the careful use of resources and the optimization of performance promoting rooms. The main emphasis in this case is on the well-being of humans, promoting their performance and hence their efficiency, and on achieving high exergetic efficiency.

Energy saving in buildings by using the exhaust and ventilation air for cooling of photovoltaic panels

A building integrated photovoltaic-thermal (BIPVT) setup has been developed for using the cooling potential of ventilation and exhaust airs in buildings for cooling the photovoltaic (PV) panels and also heating the ventilation air by heat rejection of PV panels. The setup has been tested numerically for the Kerman city located in Kerman province in the south of Iran. Results showed that, the exhaust and ventilation airs in heating ventilating air conditioning systems can be used as the cooling fluid of the PV panels and increase their efficiency. On the other hand, the heat rejection of the PV panels could provide some part of the ventilation air heating load.

An exergy application for analysis of buildings and HVAC systems

The paper presents an extended method for exergy analysis of buildings and Heating Ventilation Air Conditioning (HVAC) systems, according to an energy demand build-up model from the building side to the energy supply side. The HVAC systems comprise a thermal energy emission and control system, a thermal distribution system, an electricity distribution system and an energy conversion system. Energy and exergy that are required by a building and a HVAC system are posed into the external part and classified by different forms of energy carriers. The external part is out of the boundary of the study. The method is illustrated with an office building equipped with low-temperature heating and high-temperature cooling systems situated in the Netherlands. Thermal exergy and thermal energy demands of the building and thermal energy and thermal exergy losses occurring in the HVAC systems are discussed. The building and the HVAC systems to be considered meet standard Dutch energy performance regulations. Nevertheless their overall exergy efficiencies are low in both cases (17.15% and 6.81% subsequently). The exergy analysis also pinpoints that the thermal energy emission and control system and the energy conversion system are the main causes of the exergy inefficiencies in the heating and cooling cases, respectively.

Applying computer-based simulation to energy auditing: A case study

Through a case study, this research explores an approach, which uses computer simulation technology, to evaluate different energy conservation alternatives and to assist facility managers to select reliable and feasible solutions. The subject facility is located in the Southeast region of the United States. One of the major challenges and operation goals of the General Services Administration, who manages the facility, is for that facility to achieve the Energy Star designation. However, due to the complexity of the facility, the requirements from building occupants, as well as other difficulties, finding a path for optimizing the operation of the facility in order to achieve the Energy Star designation is not always easy. This project uses eQuest, a simulation software tool, to create a “virtual environment”, in which the operations of the HVAC (heating ventilation air-conditioning) system and the lighting of the facility are studied. Subsequently, recommendations initially made by experts through traditional energy audit approaches are evaluated in the “virtual environment” in order to determine the best solution to achieve the goal of the facility managers. This paper discusses major aspects of the project, including the challenges, the values and the limitations of applying computer simulation techniques in such a facility with complicated structural, occupancy and operation features.