Hasil untuk "Heating and ventilation. Air conditioning"

Taesuk Mun, Chanho Noh, Sung-Eun Lee

Large-scale lithium-ion energy storage systems (ESSs) are indispensable for renewable energy integration and grid support, yet ensuring long-term reliability under field conditions remains challenging. This study investigates degradation trends in a 50 MW-class ESS deployed on Jeju Island, South Korea, focusing on two indicators: direct current internal resistance (DCIR) and state-of-health (SOH). Annual round-trip (capacity) and hybrid pulse power characterization (HPPC) tests conducted from 2023 to 2025 quantified capacity fade and resistance growth. A polynomial-regression-based temperature compensation was applied—compensating DCIR to 23 °C and SOH to 30 °C—which reduced environmental scatter and clarified year-to-year degradation trends. Beyond mean shifts, intra-bank variability increased over time, indicating rising internal imbalance. A focused case study (Bank 03-01) revealed concurrent SOH decline and DCIR escalation localized near specific racks; spatial maps linked this hotspot to heating, ventilation, and air conditioning (HVAC)-driven airflow asymmetry and episodic fan operation. These findings underscore the importance of combining temperature compensation, variability-based diagnostics, and spatial visualization in field ESS monitoring. The proposed methodology provides practical insights for the early detection of abnormal degradation and supports lifecycle management of utility-scale ESSs under real-world conditions.

Laura Cirrincione, Gianluca Scaccianoce, Marco Vocciante

This work reviews and discusses experimental and simulative studies related to nanofluid applications in buildings energy systems and envelope components, including photovoltaic thermal systems, Heating, Ventilation and Air Conditioning (HVAC) systems, thermal energy storage systems and windows. An overall review of the current studies available in the literature has been conducted, providing an overview of the potential benefits of using the main nanofluid-based techniques in the building sector, with reference to both energy and environmental considerations. The results show promising prospects for future developments, proposing the use of nanofluids for applications in buildings as a viable and effective sustainable solution, in line with what is included in the most relevant energy and environmental initiatives, such as the Sustainable Development Goals (SDGs) and EU Green Deal.

LI Hang, ZHOU Xun, LUO Jiangguo et al.

[Objective] Subway carriage fire accidents often cause heavy loss of life and property, while the early detection of subway carriage fire can effectively ensure passenger′s lives. It is necessary to conduct research on this issue in different seasons under the environment of supply-return air. [Method] A full-scale subway carriage numerical simulation model and an HVAC (heating, ventilation and air conditioning) system including an air supply system, an exhaust system, and a return air system is established. Referring to three scenarios of natural ventilation, normal operation ventilation in different seasons, and carriage fires, the influence of HVAC system supply-return air in different seasons on the subway carriage airflow field and the fire early detection is analyzed. [Result & Conclusion] The characteristics of the subway carriage internal airflow field vary significantly under different seasonal operational ventilation. In the winter wind mode, heating is supplied to the carriages, resulting in stratified circulation of air with different temperatures between the upper and lower layers of the carriage during the stable period. Conversely, in the summer wind mode, cooling is provided to the interior of the carriages, resulting in a relatively uniform airflow pattern during the stable period compared to the winter wind mode. During a fire incident, smoke generated in the summer wind mode exhibits a faster smoke layer descent rate, while in the winter wind mode, the smoke spreads in a faster speed towards the sides of the carriages. As seen in the established model, the summer wind mode requires a shorter fire response time compared to the winter wind mode.

T. T. Moghadam, Carlos E. Ochoa Morales, Maria J. Lopez Zambrano et al.

New COVID-19 ventilation guidelines have resulted in higher energy consumption to maintain indoor air quality (IAQ), and energy efficiency has become a secondary concern. Despite the significance of the studies conducted on COVID-19 ventilation requirements, a comprehensive investigation of the associated energy challenges has not been discussed. This study aims to present a critical systematic review of the Coronavirus viral spreading risk mitigation through ventilation systems (VS) and its relation to energy use. COVID-19 heating, ventilation and air conditioning (HVAC)-related countermeasures proposed by industry professionals have been reviewed and their influence on operating VS and energy consumption have also been discussed. A critical review analysis was then conducted on publications from 2020 to 2022. Four research questions (RQs) have been selected for this review concerning i) maturity of the existing literature, ii) building types and occupancy profile, iii) ventilation types and effective control strategies and iv) challenges and related causes. The results reveal that employing HVAC auxiliary equipment is mostly effective and increased fresh air supply is the most significant challenge associated with increased energy consumption due to maintaining IAQ. Future studies should focus on novel approaches toward solving the apparently conflicting objectives of minimizing energy consumption and maximizing IAQ. Also, effective ventilation control strategies should be assessed in various buildings with different occupancy densities. The implications of this study can be useful for future development of this topic not only to enhance the energy efficiency of the VS but also to enable more resiliency and health in buildings.

Zhang Yi, Cui Siqi, Bai Jing et al.

To address the issues of the high-energy consumption of traditional air conditioners in communication cabinets, disordered airflow organization in cabinets, and poor temperature control effect of the baseband unit (BBU), this study integrates air-conditioning with heat pipes for communication cabinets using a temperature control system with heat pipe cooling as the primary cold source and vapor compression air conditioners as the supplementary cold source. Floor ventilation with air return from the ceiling is adopted with high wind speed and internal circulation. The unit was applied to a communication base station in Zhengzhou, and field testing results showed that under the short-term high-temperature condition during the transition season, the average working temperature of the BBU in operation mode 1 was 38.2 ℃, and the maximum outlet temperature was 46.5 ℃. Moreover, under the normal working conditions of the transition season, the average working temperature of the BBU regulated by operating mode 2 was 29.5 ℃, and the maximum air temperature was 41.3 ℃, which met the temperature control requirements of relevant standards and ensured the safe operation of BBU. Compared with those of the traditional air conditioner of the communication cabinet, the compressor operation ratio of the air-conditioning heat pipe integrated equipment in operation modes 1 and 2 was 24.9% and 0; the energy saving rate was 57.3% and 71.9%; the power usage efficiency (PUE) was 1.43 and 1.19, respectively. The comprehensive energy saving in the transition season was 71.3%, and the PUE was 1.20.

Andrzej Szczurek, Dawid Gonstał, Monika Maciejewska

This work presents a multisensor device which is intended as an element of IoT for indoor environment (IE) monitoring. It is a portable, small-size, lightweight, energy-efficient direct-reading instrument. The device has an innovative design and construction. It offers real-time measurements of a wide spectrum of physical and chemical quantities (light intensity, temperature, relative humidity, pressure, CO₂ concentration, content of volatile organic compounds including formaldehyde, NO₂, and particulate matter), data storage (microSD; server as an option), transmission (WiFi; GSM and Ethernet as options), and visualization (smartphone application; PC as an option). Commercial low-cost sensors were utilized, which have been arranged in the individual sensing modules. In the case of gas sensors, dynamic exposure was chosen to ensure a minimum response time. The MQTT protocol was applied for data transmission and communication with other devices, as well as with the user. The multisensor device can collect huge amounts of data about the indoor environment to provide the respective information to the IoT. The device can be configured to control actuators of various auxiliary devices and equipment including external systems used for ventilation, heating, and air conditioning. The prototype is fully operational. The exemplary results of IE monitoring were shown.

Luca Borro, L. Mazzei, M. Raponi et al.

Background: About 15 million people worldwide were affected by the Sars-Cov-2 infection, which already caused 600,000 deaths. This virus is mainly transmitted through exhalations from the airways of infected persons, so that Heating, Ventilation and Air Conditioning (HVAC) systems might play a role in spreading the infection in indoor environments. Methods: We modelled the role of HVAC systems in the diffusion of the contagion through a Computational Fluid Dynamics (CFD) simulations of cough at the Vatican State childrens hospital Bambino Gesu. Both waiting rooms and hospital rooms were modeled as indoor scenarios. A specific Infection-Index parameter was used to estimate the amount of contaminated air inhaled by each person present in the simulated indoor scenarios. The potential role of exhaust air ventilation systems placed above the coughing patients mouth was also assessed. Results: Our CFD-based simulations show that HVAC air-flow remarkably enhance infected droplets diffusion in the whole indoor environment within 25 seconds from the cough event, despite the observed dilution of saliva particles containing the virus. In the waiting room simulation, Infection-Index parameter increases the faster the higher the HVAC airflow. Greater flows of air conditioning correspond to greater diffusion of the infected droplets. The proper use of Local Exhaust Ventilation systems (LEV) simulated in the hospital room was associated to a complete reduction of infected droplets spreading from the patient s mouth in the first 0.5 seconds following the cough event. In the hospital room, the use of LEV system completely reduced the index computed for the patient hospitalized at the bed next to the spreader, with a decreased possibility of contagion. Conclusions: CFD-based simulations for indoor environment can be useful to optimize air conditioning flow and to predict the contagion risk both in hospitals/ambulatories and in other public/private settings.

P. Tien, S. Wei, Tianshu Liu et al.

A. Gurubalan, C. Simonson

Abstract Liquid desiccant air conditioning systems (LDAS) are an energy-efficient and eco-friendly alternative to conventional air conditioning systems. The performance of a LDAS significantly depends on its simultaneous heat and mass transfer components, namely dehumidifier and regenerator. These components are referred to as liquid desiccant energy exchangers (LDEEs) since the working fluids (air and desiccant) exchange both heat and moisture. There has been a lot of research on LDEEs over the last two decades to improve their performance, thereby enhancing the efficiency of the LDAS. The main objective of this comprehensive review paper is to summarize the developments of LDEEs. The desiccant material, and design, operating, and performance parameters of LDEEs are explained in detail. Even though a lot of research has been done on LDEEs, they are not much utilized in the practical heating, ventilation, and air conditioning (HVAC) systems. To address this issue, future research should prioritize its focus on (i) practical problems of LDEEs such as cross contamination, and leakage and blockage of the membrane, (ii) long term performance study in the practical systems, (iii) noncorrosive and inexpensive solution, (iv) compatible material for efficient heat and mass transfer, and (v) generalized design and performance control methodology. The discussions presented in this communication will be useful to ascertain the crucial research gaps that need to be addressed by future research studies.

J. Hunt, Natália de Assis Brasil Weber, Behnam Zakeri et al.

In tropical climates, the energy consumed by heating, ventilation and air conditioning can exceed 50% of the total energy consumption of a building. The demand for cooling is rising steadily, driven by global warming and rapidly increasing living standards in developing economies. In addition, there is a rise in water demand due to population increase, life quality, and global warming. Coastal areas with narrow continental shelves are the perfect site for implementing Seawater Air Conditioning (SWAC), a renewable and low CO2 emission cooling process. This article proposes the combination of SWAC and reverse osmosis (RO) desalination with the objective of providing desalinated cold water for integrated water supply and cooling services. This combination was named Deep Seawater Cooling and Desalination (DSCD). It was found that DSCD can supply 49 MWt of cooling and 1 m3/s of water simultaneously with an electricity consumption of 12 MWe. DSCD has several benefits compared to SWAC and RO individually, such as in how the cooling service and water supply are delivered together, reducing distribution costs. A case study was performed in Male, Maldives. It shows that the technology has substantial potential to contribute to the sustainable development of tropical islands.

Ihab Omar, A. Mohsen, Karrar A. Hammoodi et al.

The objective of this study is to provide a simplified worksheet based on the Total Equivalent Temperature Difference (TETD) Approach to estimate a building’s cooling load under Iraqi climate conditions. The heating, ventilation and air conditioning (HVAC) system was applied to scientific laboratories at the College of Engineering, University of Warith Al-Anbiyaa, Karbala, Iraq. The study estimates the cooling load of the building, which consists of 10 zones. Cooling load elements such as ventilation, lighting, walls, floors, roofs, windows, infiltration, and human factors were considered. The worksheet provides an appropriate alternative for easy and fast prediction within Iraq's climate conditions.

Zou Huiming, Tang Xinbin, Tang Zuohang et al.

In this study, a CO2 heat pump system test bench for electric vehicles with an oil circulation rate testing device was built to investigate the influence of the oil circulation rate on the performance of the compressor and the heat pump under typical vehicle operating conditions. Under refrigeration conditions, the increase in the oil circulation rate from 1.17% to 5.26% increased the volumetric and isentropic efficiencies of the compressor by 13.6% and 5.6%, respectively, Under heating conditions, when increasing the oil circulation rate from 1.51% to 6.68%, the volumetric and isentropic efficiencies of the compressor increased by 7.19% and 15.7%, respectively, while the discharge temperature of the compressor decreased from 155.5 °C to 146 °C. Unlike the flow resistance and heat exchange capacity of the air cooler in the high-temperature section, the oil circulation rate exhibited a significant effect on the evaporation process in the low-temperature section. The analysis of the influence of the oil circulation rate on the overall performance of the heat pump system demonstrated that the heat pump system performance improved when the oil circulation rate is approximately 4%.

Haofu Chen, Zhuangbo Feng, Shi-jie Cao

Rational and scientific design of indoor air conditioning is essential. In the design of Heating, Ventilating and Air Conditioning system, air-supply speed (ventilation rate) and air-supply temperature are the two most important parameters. In the current study, numerical simulations and experimental measurements were adopted to investigate the influences of ventilation mode, air-supply velocity and air-supply temperature on indoor thermal comfort as well as building energy consumption in summer. Different ventilation modes (up supply and down exit, ceiling supply and ceiling exit) were considered in modelling. Based on the simulation and experimental results, dimensionless index G r / R e 2 is proposed, which represents the ratio of buoyancy weighting force to inertial force. This index can be used as a pre-evaluation index of indoor thermal comfort in preliminary design of air conditioning. It is an indicator to judge the working conditions in cooling-ventilated rooms. When 10 - 6 < Gr R e 2 < 10 - 5 , the settlement and diffusion effects of indoor airflow reach a good level, which means that the parameter setting could provide a comfortable indoor thermal environment. The dimensionless number G r / R e 2 is a theoretically based tool in the pre-evaluation of indoor thermal environment, providing guidance for setting of ventilation design parameters.

Yamile Díaz Torres, H. Herrera, M. A. A. Plasencia et al.

The tourism sector is one of the main worldwide economic sectors with sustained growth, demonstrating its strength and esilience. In this sector, energy uses have increased to ensure quality, guest comfort, and rate level requirements being a uilding with great energy consumption. Several factors influence and can produce a significant variation in hotel consumption ven in facilities located in the same region; the difference in a four-star hotel can reach 114 kWh/m2/year. This paper deals ith related aspects such as hotel design, operation, type of service, occupancy patterns, operating point and efficiency of a eating, ventilation, and air conditioning (HVAC) system where 30 to 50% of the energy is consumed. Also, previous works ased on the implementation of non-conventional energy resources such as photovoltaics projects to replace fuel dependence and igh costs in electricity bills were reviewed. where there are savings of up to 30% in electricity and 60% in gas consumption. owever, the initial capital investment and payback period are high and require new features to be considered in these facilities. c 2020 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/). eer-review under responsibility of the scientific committee of the Tmrees, EURACA, 2020. eywords: Hotels; Facilities; Heating ventilation and air conditioned (HVAC) system; Energy uses

Haibin Wei, Dong Yang, Yuanhao Guo et al.

Xiaozhou Wu, L. Fang, B. Olesen et al.

L. Weinstein, M. Cacan, P. M. So et al.

J. Mitchell, J. Braun

Yu Guoqing, Jia Wenzhe, Zhao Yanjie

According to the heat transfer between radiant ceiling unit and surrounding environment, based on the reasonable simplification of configuration of radiant ceilings, set up theoretical calculation models of single piece of the capillary cooling radiant ceiling unit and two units in series combination to calculate their cooling capacities. Then tests their cooling capacities under the condition of 25℃ room temperature, 15~19℃ supply water temperature. The comparison between measured data and calculation results show that theoretically calculated cooling capacity of single unit and of two series-connected units approach the experimental testing data, which shows that the theoretical calculation models are reasonable and feasible and can be used to predict the cooling capacities under real conditions.