scholarly journals Performance analysis of an active diffuser in mixing ventilation for cell office by using numerical approach

2019 ◽  
Vol 111 ◽  
pp. 04033
Author(s):  
Mehrdad Rabani ◽  
Habtamu B. Madessa ◽  
Natasa Nord ◽  
Peter Schild
Keyword(s):  
New Technologies ◽  
Ventilation System ◽  
Winter Season ◽  
Heating System ◽  
Numerical Approach ◽  
Energy Utilization ◽  
Space Heating ◽  
Airflow Rate ◽  
Archimedes Number ◽  
House Standard

Energy efficiency in buildings is nowadays considered as an essential step to reduce CO2 emissions and energy utilization. At the same time, new technologies such as building space heating using active air heating has simplified the heating system without any need for backup heating system. This study investigated the thermal stratification of mixing ventilation system equipped with a radial active supply diffuser for space heating of an office room designed according to the Norwegian passive house standard by using Star-CCM+. Simulations were performed for different supply airflow rates with corresponding slot openings of the active diffuser at different outdoor conditions for winter season. The combined effect of the supply airflow rate and the outdoor air temperature were also described in the form of Archimedes number (Ar). The results showed that adopting active diffuser could avoid the temperature stratification for all the simulated cases by preserving the throw length of supply jet. In addition, the lowest temperature effectiveness of 38% occurred when a high supply temperature was used in the coldest day. Furthermore, with the supply temperature 24 °C, the airflow rate 49.4 l/s at the outdoor temperature -15 °C would result in a favorable average of PMV ⁓ 0.497.

Numerical and Experimental Modeling of Indoor Air Quality Inside a Conditioned Space with Mechanical Ventilation and DX-Air Conditioner

2020 ◽  
Vol 38 (9A) ◽  
pp. 1257-1275
Author(s):  
Wisam M. Mareed ◽  
Hasanen M. Hussen
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Ventilation System ◽  
Thermal Conditions ◽  
Airflow Rate ◽  
Air Conditioner ◽  
Breathing Zone ◽  
Lecture Room ◽  
Ventilation Performance

 Elevated CO2 rates in a building affect the health of the occupant. This paper deals with an experimental and numerical analysis conducted in a full-scale test room located in the Department of Mechanical Engineering at the University of Technology. The experiments and CFD were conducted for analyzing ventilation performance. It is a study on the effect of the discharge airflow rate of the ceiling type air-conditioner on ventilation performance in the lecture room with the mixing ventilation. Most obtained findings show that database and questionnaires analyzed prefer heights between 0.2 m to 1.2 m in the middle of an occupied zone and breathing zone height of between 0.75 m to 1.8 given in the literature surveyed. It is noticed the mismatch of internal conditions with thermal comfort, and indoor air quality recommended by [ASHRAE Standard 62, ANSI / ASHRAE Standard 55-2010]. CFD simulations have been carried to provide insights on the indoor air quality and comfort conditions throughout the classroom. Particle concentrations, thermal conditions, and modified ventilation system solutions are reported.

scholarly journals Overview of Solutions for the Low-Temperature Operation of Domestic Hot-Water Systems with a Circulation Loop

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3350
Author(s):  
Theofanis Benakopoulos ◽  
William Vergo ◽  
Michele Tunzi ◽  
Robbe Salenbien ◽  
Svend Svendsen
Keyword(s):  
Low Temperature ◽  
Heat Loss ◽  
District Heating ◽  
Heating System ◽  
Hot Water ◽  
Heating Power ◽  
Circulation Loop ◽  
Space Heating ◽  
District Heating System ◽  
Domestic Hot Water

The operation of typical domestic hot water (DHW) systems with a storage tank and circulation loop, according to the regulations for hygiene and comfort, results in a significant heat demand at high operating temperatures that leads to high return temperatures to the district heating system. This article presents the potential for the low-temperature operation of new DHW solutions based on energy balance calculations and some tests in real buildings. The main results are three recommended solutions depending on combinations of the following three criteria: district heating supply temperature, relative circulation heat loss due to the use of hot water, and the existence of a low-temperature space heating system. The first solution, based on a heating power limitation in DHW tanks, with a safety functionality, may secure the required DHW temperature at all times, resulting in the limited heating power of the tank, extended reheating periods, and a DH return temperature of below 30 °C. The second solution, based on the redirection of the return flow from the DHW system to the low-temperature space heating system, can cool the return temperature to the level of the space heating system return temperature below 35 °C. The third solution, based on the use of a micro-booster heat pump system, can deliver circulation heat loss and result in a low return temperature below 35 °C. These solutions can help in the transition to low-temperature district heating.

Experimental Study of Notoginseng Drying Based on a Solar Air Heating System

2011 ◽  
Vol 71-78 ◽  
pp. 2073-2076
Author(s):  
Fen E Hu ◽  
Zhi Juan Wang
Keyword(s):  
Winter Season ◽  
Heating System ◽  
Solar Drying ◽  
Mass Rate ◽  
Drying Time ◽  
Air Heating ◽  
Solar Air Collector ◽  
Air Blower ◽  
Drying System ◽  
Air Channels

A solar air drying system including solar air collector, drying cabinet and air blower for notoginseng drying has been constructed and tested. Two identical air solar collectors with two air channels, V-groove absorption heat plates and a single glass cover have been employed. The results of test show that the solar air collectors can obtain a good thermal performance in winter season. When the air flow mass rate is fixed at 0.0597kg·s-1, the maximum values of thermal efficiency and outlet air temperature are 76.0% and 62.2°C, respectively. The experimental analysis between two sampling notoginseng drying suggests that the solar drying is very effective, and the drying time has been shorten to about 440 minutes from 990 minutes of the traditional drying by sun. It is also observed that using the solar drying system notoginseng has a higher quality than traditional drying method.

scholarly journals Energy and Exergy Analysis of a Plane Reflector Integrated Photovoltaic-Thermal Water Heating System

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Prem Sagar Naik ◽  
Arun Palatel
Keyword(s):  
Solar Radiation ◽  
Thermal Water ◽  
Winter Season ◽  
Performance Testing ◽  
Electrical Energy ◽  
Heating System ◽  
Present System ◽  
Exergetic Efficiency ◽  
Water Heating ◽  
Electrical Output

A photovoltaic-thermal water heating system is a hybrid energy conversion device transforming the incident solar radiation to yield electrical energy and thermal energy. Plane reflectors are found to be a convenient option for enhancing the solar radiation incident on the collector plane. The present work investigates the performance of a photovoltaic-thermal water heater integrated with a plane reflector mounted on the top edge of the collector for the tropical climate of Calicut (11.25°N, 75.78°E). Performance testing of the system has been carried out for the winter season of the location. The variations in thermal and electrical output are studied for various inclination angles of the reflector. The system performance is evaluated on the basis of system energy efficiency and exergetic efficiency. It is observed that there is a significant enhancement in the thermal and electrical output of the system with the integration of the reflector as compared to the system without the reflector. For the present system, the reflector tilt angle in the range of 85–100° has been found to be suitable in terms of enhanced system output and exergetic efficiency for the winter conditions of Calicut.

Atverčiant primirštą Lietuvos kultūros puslapį: Vilniaus modernizmo atspindžiai pavelde

2021 ◽  
pp. 213-229
Author(s):  
Edita Povilaitytė-Leliugienė
Keyword(s):  
Interwar Period ◽  
New Technologies ◽  
Heating System ◽  
Modern Architecture ◽  
Heritage Preservation ◽  
Urban Structures ◽  
General Law ◽  
Central Heating ◽  
Heritage Buildings ◽  
Modern Technologies

The analyses of interwar Vilnius heritage preservation, research, and maintenance concentrated mostly on discussions about the general law, state tendency, and case studies of good and bad practices. However, the more modern heritage preservation, research, or maintenance theories and aspects during the interwar period were neglected. Therefore, this article aims to analyse if modern technologies, ideas, and methods in the heritage research and maintenance (mostly in the reconstructions and adaptation of heritage buildings for new purposes) projects were adapted or not in interwar Vilnius. According to this aim, the article analyses a few heritage maintenance works and emphasises how architects used new technologies, modern architecture details, and ideas in the heritage maintenance projects and their realisation. Technologies as central heating system, electrification, canalisation, toilets, or bright interiors, wide air-spaces were inseparable from modernism perspective. The architecture of buildings and urban structures were modernised and improved for better living quality. Also, ideas and technologies did not avoid the heritage objects, especially civil buildings as Vilnius Town Hall, squares as Cathedral square, defensive heritage object as Vilnius Upper Castle. However, the analysis maintains that modern technologies were used moderately and kept a respectful tone with the authentic heritage, whole complex, and elements.

Modeling of a Space Heating System Coupled with Underground Energy Storage

2018 ◽  
Vol 51 (3) ◽  
pp. 373-400
Author(s):  
Guoxiang Zhao ◽  
Kewen Li ◽  
Changwei Liu ◽  
Lin Jia ◽  
Bheki Mahlalela Mahlalela
Keyword(s):  
Energy Storage ◽  
Heating System ◽  
Space Heating

scholarly journals EVALUATION OF COMBINED PRODUCTION OF HEAT AND ELECTRICITY ON THE COGENERATION UNIT

2021 ◽  
Vol 2021 (6) ◽  
pp. 5312-5316
Author(s):  
MIROSLAV RIMAR ◽  
◽  
MARCEL FEDA ◽  
ANDRII KULIKOV ◽  
MILAN ABRAHAM ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Natural Environment ◽  
Energy Production ◽  
Renewable Energy Sources ◽  
Winter Season ◽  
Main Idea ◽  
Heating System ◽  
Energy Sources ◽  
Central Heating

The purpose of currently contribution is to analyse and compare effectivity of cogeneration unit in each summer and winter season. The main idea of combined heat and energy production is to reduce usage of primary fuels and with that connected reduction of pollutions due to the integration of renewable energy sources and with regard to the natural environment. Presented contribution is dedicated on issue on the operation of a cogeneration unit integrated in central heating system.

scholarly journals Heat recovery by means of a ventilation unit

2021 ◽  
Vol 263 ◽  
pp. 04025
Author(s):  
Dmitrii Khlopitsyn ◽  
Andrey Rymarov
Keyword(s):  
Energy Consumption ◽  
Energy Saving ◽  
Heat Recovery ◽  
New Technologies ◽  
Ventilation System ◽  
New Developments ◽  
Before And After ◽  
Save Energy ◽  
Recuperative Heat Exchanger ◽  
Air Removal

Energy consumption all over the world is constantly growing. To save energy, new technologies are being developed for the efficient use of energy resources. The goal of all new developments is to use less energy to provide the same level of energy supply for technological processes or buildings. The problem of energy saving is relevant for the ventilation system. Together with the removed air, a large amount of heat is lost, which is not advisable. In order to avoid these losses, heat recuperators began to be used, heating the cold supply air due to the warm air removed from the room. This development belongs to the field of energy saving. The goal is to increase efficiency by reheating the air after the heater with the help of a recuperator for a given temperature difference in the supply air before and after the recuperative heat exchanger. The development is a design of a ventilation unit with air removal and supply air ducts, combined into one housing with a separate, according to the “screw” principle, heat transfer wall, for use in the ventilation system in order to ensure an optimal microclimate in the room. Thus, as a result of using the presented device, the efficiency of the room ventilation unit is increased by reducing the energy consumption for heating the supply air with a heater.

scholarly journals SOLAR ENERGY: A POTENTIAL SOURCE OF RENEWABLE AND CLEAN ENERGY

2018 ◽  
Vol 6 (8) ◽  
pp. 214-217
Author(s):  
Deepak Aryal
Keyword(s):  
Solar Energy ◽  
Urban Areas ◽  
Sunshine Duration ◽  
Winter Season ◽  
Clean Energy ◽  
Energy Utilization ◽  
Rural And Urban Areas ◽  
Rural And Urban ◽  
Solar Energy Utilization ◽  
Analytical Review

This paper reports analytical review results on the global and national importance of solar energy as a clean and renewable source of energy. Pre-monsoon and post monsoon seasons have higher mean monthly sunshine duration (about 8 hours/day) than summer (about 5 hours/day) and winter (about 7 hours/day) seasons in Kathmandu. The lowest sunshine duration during summer season is attributed to the effect of monsoonal clouds during that period. Pre-monsoon and monsoon seasons receive solar energy of about 250 W/m2 and 200 W/m2 respectively. The winter season receives the least amount of solar radiation (about 150 W/m2). Results show high prospect of solar energy utilization both in rural and urban areas of Nepal.

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