Energy Recovery Ventilator Research Articles

CO2デマンド制御を組み込んだ全熱交換型換気システムの性能評価 (第10報) 夏期調査に基づく換気負荷低減効果の検証

CO2デマンド制御を組み込んだ全熱交換型換気システムの性能評価 (第10報) 夏期調査に基づく換気負荷低減効果の検証

Impact of Outdoor Air Exchange Rates on Sleep Quality and the Next-Day Performance with Application of Energy Recovery Ventilator

Sleep quality can affect human health and the next-day performance. High indoor CO2 concentration levels due to insufficient supplied air ventilation could cause poor sleep quality. Bedrooms in condominium in Thailand commonly use a wall mounted split type system without supplied outdoor air ventilation. The rooms are typically constructed having airtight envelope which have air infiltration rates ranging 0.4-0.64 ACH. This study aims to evaluate the impact of increased ventilation rates on sleep quality and the next-day performance, which the surveys were collected from two occupants living in a one bedroom condominium. The field measurement and survey were conducted for twenty days with supplied outdoor airflow rates at 0, 40, and 60 m3 hr-1 through an energy recovery ventilator (ERV). The room air exchange rates were calculated from a linear regression method obtained from a decay tracer gas technique using indoor carbon dioxide generated by occupants. To overcome the maximum limit of CO2 concentration level specified in the standard health guidelines, the ERV unit has to supply outdoor air ventilation rate at 60 m3 hr-1. Overall, the increase of outdoor air ventilation rates can improve sleep quality by 2-13 percent and occupants have better work performance in the next day by 2-20 percent. The increase of outdoor air ventilation through the ERV unit does not affect indoor relative humidity.

Performance study of sodium alginate-nonwoven fabric composite membranes for dehumidification

A novel composite membrane is proposed to improve the dehumidification performance of the membrane-based energy recovery ventilator (ERV). In this study, the composite materials based on nonwoven fabrics, sodium alginate and lithium chloride (LiCl) were fabricated. Nonwoven fabrics were adopted as supporting constructions; sodium alginate and LiCl were the corresponding active layer and hydrophilic additive. Membranes with different LiCl mass fraction were tested and analyzed to evaluate practical performance when applied in the ERV. Results show that the highest vapor permeance of the composite membrane is 29.8×10−8kg/m2·s·Pa, 10 times higher than that of composite one without LiCl. Water solubility declines to 20.6%, which demonstrates a certain waterproofness of membranes. Besides, simultaneous thermal analysis shows that LiCl accelerates evaporation rate of bound water. Furthermore, two ERVs with different composite membranes are fabricated and characterized by measuring their sensible, latent and enthalpy efficiencies. It is found that these three efficiencies can reach up to 83.9%, 87.4% and 86.7% under summer condition, and 80.8%, 81.7%, and 81.1% under the winter condition, respectively.

中規模オフィスビルを対象とした全熱交換器の空調消費電力削減効果に関する実測研究 : 第3報-全熱交換器モデルを介したCFDとBESの連成解析

中規模オフィスビルを対象とした全熱交換器の空調消費電力削減効果に関する実測研究 : 第3報-全熱交換器モデルを介したCFDとBESの連成解析

CO_2デマンド制御を組み込んだ全熱交換型換気システムの開発と実測による省エネルギー性能検証 : 第1報-大学研究室を対象とした夏期冷房時の換気負荷削減効果

CO_2デマンド制御を組み込んだ全熱交換型換気システムの開発と実測による省エネルギー性能検証 : 第1報-大学研究室を対象とした夏期冷房時の換気負荷削減効果

中規模オフィスビルを対象とした全熱交換器の空調消費電力削減効果に関する実測研究 : 第2報-夏期冷房時を対象とした実測と削減効果

中規模オフィスビルを対象とした全熱交換器の空調消費電力削減効果に関する実測研究 : 第2報-夏期冷房時を対象とした実測と削減効果

中規模オフィスビルを対象とした全熱交換器の空調消費電力削減効果に関する実測研究 : 第1報-冬期暖房時を対象とした実測と削減効果

中規模オフィスビルを対象とした全熱交換器の空調消費電力削減効果に関する実測研究 : 第1報-冬期暖房時を対象とした実測と削減効果

CO_2デマンド制御を組み込んだ全熱交換型換気システムの開発と実測による省エネルギー性能検証 : 第2報-大学研究室を対象とした冬期暖房時の換気負荷削減効果

CO_2デマンド制御を組み込んだ全熱交換型換気システムの開発と実測による省エネルギー性能検証 : 第2報-大学研究室を対象とした冬期暖房時の換気負荷削減効果

J-56 CO2ディマンド制御を組み込んだ熱交換型換気システムの性能評価 : (第1報)大学研究室スペースを対象とした実測概要と全熱交換器の現場性能

J-56 CO2ディマンド制御を組み込んだ熱交換型換気システムの性能評価 : (第1報)大学研究室スペースを対象とした実測概要と全熱交換器の現場性能

Evaluation of governing heat and mass transfer resistance in membrane-based energy recovery ventilators with internal support structures

Energy recovery ventilators are an effective way to reduce energy consumption in buildings while satisfying ventilation standards. As membrane technology and manufacturing methods improve, membrane-based energy recovery ventilators are seeing increased market penetration. In the present study, the feasibility of membrane energy recovery ventilators designed to fit in a commercial building wall cavity is investigated. A heat and mass transfer resistance and pressure drop model is developed for a low aspect ratio (width/height) exchanger and is used to evaluate the sensible and latent effectiveness of a counter-flow energy recovery ventilator with internal support structures. The performance of strip-fin and pin-fin structures are compared and dominant heat and mass transfer resistances are investigated. It is shown that for all cases the sensible heat transfer is dominated by the convective resistance while the dominant mass transfer resistance shifted to the membrane at smaller hydraulic diameters. The results suggest that as membrane technology improves, enhancements to the airside heat and mass transfer coefficients will be required to continue to realize performance gains.

Particulate fouling assessment in membrane based air-to-air energy exchangers

The impact of air-side particulate fouling on the performance of membrane-based, fixed-plate energy recovery ventilators (ERVs) is investigated for both fine and coarse (0.3–10μm) as well as ultrafine (∼0.1μm) aerosols. Two residential size cross-flow ERV exchanger cores were fouled with ISO A3 medium test dust. It was found that coarse dust loading, equivalent to that of a few years of exposure in a heavily polluted environment, has minimal impact on the performance of ERV exchanger cores. In both cases, the sensible and latent effectiveness were actually slightly enhanced due to boundary layer thinning and additional turbulence potentially caused by the dust layer. Heavy dust loadings, in the absence of appropriate filtration upstream, may result in a fan energy penalty (∼50%) due to the added pressure drop across the exchanger cores.Samples of three different membrane transport media, extracted from commercial HVAC ERV exchanger cores, were loaded with graphite and NaCl aerosol nanoparticles. Accelerated loading experiments were conducted in a laboratory apparatus to simulate several years of fouling in the field. Initial and post-loading water vapor permeance through the membrane samples were experimentally determined for each loading to quantify the effects of fouling. The impact of relative humidity on the performance of loaded membranes was also studied by exposing membranes loaded with particles in dry air to an elevated RH of 75%, leading to surface condensation. The experiments show that the deposition of particles in dry air can only affect the membrane when the fouling is severe enough to form a cake layer on the membrane surface comparable to the thickness of the membrane. In the case of membranes loaded with hygroscopic salt particles, surface condensation at high RH values can lead to vapor permeance reductions of up to 15% well before the cake layer formation phase of fouling, whilst no permeance reduction was observed for membranes loaded with non-hygroscopic graphite particles. This indicates a net porosity reduction in the microporous substrate layer of exposed salt-loaded samples. A pore-narrowing process of the substrate layer, due to the mobilization of salt particles in aqueous form, is a potential explanation for these observations.

Analysis of the Internal Environment in an Enclosed Pig House as According to the Height of Duct Applied with Energy Recovery Ventilator

Analysis of the Internal Environment in an Enclosed Pig House as According to the Height of Duct Applied with Energy Recovery Ventilator

전열교환 환기시스템의 설계 지원을 위한 확률적 다기준 의사 결정 접근의 적용

전열교환 환기시스템의 설계 지원을 위한 확률적 다기준 의사 결정 접근의 적용

Control strategies for Energy Recovery Ventilators in the South of Europe for residential nZEB—Quantitative analysis of the air conditioning demand

Mechanical ventilation systems are essential for ensuring the indoor quality of air in nZEB (nearly Zero Energy Buildings) with a high level of airtightness. In cold countries, it has already been demonstrated that Heat Recovery Ventilators (HRV) recovering the sensible energy from air ventilation are needed to achieve the energy demand goals for nZEB set by Passivhaus. In tropical areas with hot temperatures and high relative humidity in the ambient air, the necessity of recovering latent and sensible energy with Energy Recovery Ventilators (ERV) has also been demonstrated. However, in warm climates with medium relative humidity levels, for example in cities located on the Mediterranean coast, the evaluation of the effectiveness of an EVR for residential buildings has to be analyzed and optimized.This article establishes the effectiveness of several control strategies for ventilation air systems including ERV with the aim of optimizing the air conditioning energy demand of dwellings located in several cities in the South of Europe. Possible control strategies have been analyzed to minimize the undesirable operation of ERVs which could otherwise increase the air conditioning energy demand for winter and summer seasons. The impact of the latent effectiveness and the effect of free-cooling on the air conditioning energy demand is also studied.

Experimental evaluation and simulation of a variable refrigerant- flow (VRF) air-conditioning system with outdoor air processing unit

Variable refrigerant flow (VRF) refers to the ability of an air-conditioning (AC) system to control the amount of refrigerant flowing to the multiple evaporators (indoor units). This study compares the actual energy use of a building, equipped with a VRF system with simulation results obtained using EnergyPlus. Also, the aim of this study is to analyze the performance related to energy and thermal comfort when the VRF system without ventilation is replaced with the VRF system with the energy recovery ventilation (ERV) or VRF system with the dedicated outside air system (DOAS). The measured power use of the VRF system is very similar to the simulated power use of the VRF system. The mean value of the difference between simulation and measured data in monthly power use in summer and winter was 3.3% and 3.6%, respectively. The yearly energy use of the VRF system without ventilation is found to be 213.6kWh/m2a. The VRF system with ERV in case 4 and the VRF system with DOAS in case 8 are found to be 16.8% and 26.0% higher than the VRF system without ventilation, respectively. Through the entire year, it was found that 17.2% of indoor air condition data provided by the VRF system without ventilation in the winter and 16.2% of the data in the summer fall within the ASHRAE winter and summer comfort zones. In order to improve the thermal comfort, the setpoint temperature in winter needs to be increased and the humidity in summer needs to be reduced. On the other hand, it was found that 93.9% of indoor air condition data provided by the VRF system with DOAS in the winter and 83.8% of the data in the summer fall within the ASHRAE winter and summer comfort zones. When the VRF system without ventilation is replaced with the VRF system with DOAS, the thermal comfort percentage is improved during the winter and summer by 76.7% and 67.6%, respectively.

自然換気併用外気制御システムをもつ空調室の熱負荷計算法に関する研究

This paper presents a thermal load simulation method for spaces conditioned by heating, cooling and fresh air control systems combined with natural ventilation. Fresh air control systems enables free cooling, demand control ventilation and energy recovery ventilation. Natural ventilation may be carried out while spaces are conditioned by cooling equipment. For simulation of natural ventilation, many conditions which must be satisfied for natural ventilation can be considered and the under limit of space air temperature is supposed to be controlled by regulating ventilation opening area. On the other hand, natural ventilation rate is calculated under the simple conditions where airflow balance is not solved and the location of the neutral zone is assumed to be fixed. Space air temperature control by free cooling and heat recovery ventilation can be simulated. In demand control ventilation, ventilation rate is estimated in proportion of occupancy rate For heat balance simulation of multi zones where fresh air control systems combined with natural ventilation are used, a new method was developed in order to enable speedy simulation and to avoid complicated procedure. In the proposed method for iterative solution of heat balance and fresh air rate which means sum of natural ventilation rate and forced ventilation rate for free cooling, space air temperature control by regulating fresh air rate is replaced for control by a virtual heater and cooling and heating capacities are intentionally increased. This procedure suppresses iteration of calculating fresh air rate and the solution such as heating rate, cooling rate and fresh air rate can be obtained by correcting the calculated results. The proposed simulation method was applied to the building simulation engine in BEST which is a whole building energy and thermal load simulation program and the simulations for a typical office building located in Tokyo were performed. The basic effects of fresh air control techniques and natural ventilation on space thermal environment and thermal load were presented. The interaction effects of energy saving strategies such as high performance building facades, natural ventilation and fresh air control techniques were evaluated through simulations in two buildings. One is a low-performance building and the other is a high-performance building. The energy saving rate for a low-performance building is defined as the thermal load reduction achieved by adding an energy saving strategy, and that for a high-performance building is defined as the thermal load increase resulted by removing the strategy employed in the high-performance building. Although some strategies provide lower energy savings for the high-performance building than for the low-performance building, a few strategies are more effective for the high-performance building.

Performance Analysis of An Energy Flow Solar Assisted Desiccant Cooling Fittedwith Honeycomb Adsorption

A new and potentially clean technology that can be used to condition the internal environment of buildings without the use of harmful refrigerants. Unlike conventional air conditioning systems, which rely on electrical energy to drive the cooling cycle, desiccant cooling is an open heat driven cycle, which uses a desiccant wheel and thermal wheel in tandem to achieve both cooling and dehumidification. Because it is a heat driven cycle, there is the potential to use environmentally cleaner sources of energy such as gas, hot water, waste heat or any heat source, including solar thermal energy, able to elevate the air temperature to a level adequate for reactivation. Desiccant materials, which absorb moisture, can be dried, or regenerated, by adding heat supplied by natural gas, waste heat, or the sun. In most systems, a wheel that contains a desiccant turns slowly to pick up humidity from incoming air and discharge that humidity to the outdoors. Desiccant cooling can also be used in tandem with an conventional air conditioning system in which the desiccant removes humidity and the AC system provides cooling, and in energy recovery ventilators (ERV) to dehumidify incoming fresh air in the summer.

Performance characterization of the membrane-based energy recovery system

Recently, the energy conservation demand attracted much attention, due to the depletion of energy resource and environmental impact caused by the increase in energy consumption. As well know, the heating, ventilation, and air-conditioning (HVAC) systems, which provide thermal comfort for occupants in buildings, account for a significant portion of global energy demand. Energy recovery is one of the key energy-efficient technologies, which reveals to deal with the increase of energy usage in building while maintaining indoor air quality. However, in the conventional heat recovery system, the sensible heat was recovered, but the latent heat was ignored. In this work, to evaluate the total energy saving potential, a novel energy recovery ventilator (ERV) model is developed with a semi-permeable membrane which can transfer both heat and moisture. A conjugate heat and mass transfer model subject to tropical climate condition is investigated by both analytical and numerical methods. The three-dimension ERV model is comprehensively studied by CFD simulation for analysis of critical parameters, such as velocity, temperature, humidity of supply and exhaust airflows. The numerical results showed that both sensible and latent effectiveness could be gained very high. Even that the latent effectiveness is lower than sensible effectiveness, the energy saving impact by dehumidification is considerable in the tropical climate.

열회수형 환기장치의 결로방지를 위한 지역별 예열코일 용량산정 및 분석

Heat recovery ventilator and energy recovery ventilator (HRVs/ERVs) save energy load in buildings by reusing the heat from exhaust air. However, when HRVs/ERVs are operated in winter season, condensation may occur in heat exchange process causing negative influence not only on occupants but also on the performance of the system; mold and bacteria are developed through condensation causing respiratory diseases to occupants, and frosts may be developed once the condensation meets the air with the temperature under the freezing point causing the efficiency of exchangers to drop dramatically or even the breakdown of the whole system. Many methods to prevent condensation or frost have been suggested however preheating may be the simplest and the most certified method to guarantee the performance of the HRVs/ERVs systems. In this paper, variable factors for sizing the capacity of preheating coils have been verified. Also, the appropriate preheating capacity of HRVs/ERVs for different regions in Korea have been suggested based on the frost threshold temperature and the design procedure for various conditions.

Optimizing Control of Dedicated Outdoor Air Systems with Energy Recovery in Commercial Buildings

AbstractDedicated outdoor air systems (DOASs) with energy recovery ventilators (ERVs) are increasingly popular in new buildings and have the potential to greatly reduce building energy consumption through elimination of zone-level summer reheat and free preconditioning of outdoor ventilation air through energy recovery with building exhaust air, often using an enthalpy wheel heat exchanger. In practice, many of these systems, however, are run suboptimally or are designed with complex and counterintuitive configurations that require detailed engineering analysis to understand optimal control sequences. Three real-world case studies from commercial building retuning are presented where control deficiencies in DOASs with ERVs led to excess energy consumption. An analysis of the potential energy savings from correcting these deficiencies as well as a discussion of how each analysis was performed during the retuning audit is included. Energy savings can vary significantly based on the climate and the baseline ...