scholarly journals Associations between indoor soundscapes, building services and window opening behaviour during the COVID-19 lockdown

2021 ◽  
pp. 014362442110544
Author(s):  
Simone Torresin ◽  
Rossano Albatici ◽  
Francesco Aletta ◽  
Francesco Babich ◽  
Tin Oberman ◽  
...  
Keyword(s):  
Online Survey ◽  
Cooling System ◽  
Air Cooling ◽  
Cooling Systems ◽  
Acoustic Environment ◽  
Factors Associated ◽  
Significant Difference ◽  
Window Opening ◽  
And Gender ◽  
Home Workers

Results of an online survey conducted during the COVID-19 lockdown among 848 home workers living in London (United Kingdom) and in Italy are reported with a focus on (1) the impacts of building services on the perception of the acoustic environment while working and relaxing at home and (2) the factors associated with window opening behaviour. The analyses showed no significant difference in soundscape appropriateness for relaxation depending on the heating, ventilation and cooling system typologies, and in soundscape appropriateness for working from home (WFH) based on the ventilation strategy. Higher soundscape appropriateness for WFH was associated with houses equipped only with radiant floors for heating in Italy and with air-cooling systems in London. In London, air systems resulted in higher perceived dominance of noise from building services compared to other systems. Overall, rooms with less dominant sounds from building services were evaluated as more appropriate for working and relaxing. The dominance of sky or buildings from the window view, outdoor noisiness, noise sensitivity, age and gender were not significantly associated with participants’ window opening behaviour while WFH. Differently, participants viewing more vegetation from windows in Italy were more likely (odds ratio: 1.279) to keep the window open while WFH.

scholarly journals Relaxing and working from home: associations between heating, ventilation and cooling system typologies and indoor soundscape evaluation

2021 ◽  
Vol 2069 (1) ◽  
pp. 012174
Author(s):  
Simone Torresin ◽  
Rossano Albatici ◽  
Francesco Aletta ◽  
Francesco Babich ◽  
Tin Oberman ◽  
...  
Keyword(s):  
Online Survey ◽  
Cooling System ◽  
Residential Buildings ◽  
Hvac Systems ◽  
Air Cooling ◽  
Cooling Systems ◽  
Acoustic Environment ◽  
Working From Home ◽  
Window Opening ◽  
Cooling Air

Abstract Data from an online survey conducted in January 2021 by 464 participants living in London and working from home (WFH) after the COVID-19 outbreak were analysed, focusing on: (1) types of building services at home, (2) perceived sound dominance of building services, and (3) the perception of the indoor acoustic environment (i.e. the indoor soundscape) in relation to two main activities, i.e. WFH and relaxation. Results show that most of participants’ houses had radiators for heating and relied on window opening for ventilation and cooling. Air systems (e.g., HVAC systems) resulted in higher perceived dominance compared to other systems, but only when evaluated for WFH. Sound dominance from building services was in turn related to soundscape evaluation. Spaces with less dominant sounds from building services were more appropriate for both WFH and relaxation, and spaces with fewer dominant sounds were assessed better, but just for WFH. Participants’ evaluations generally did not differ according to building service typology. The presence of air-cooling systems was associated with better perceived sound environments, most likely due to better acoustics conditions in newly built or retrofitted dwellings, more probably equipped with air cooling systems. Preliminary findings point out the importance of carefully considering the dominance of sounds by building services, especially for air systems, in relation to traditional and new uses of residential buildings.

Inlet Air Cooling Applied to Combined Cycle Power Plants: Influence of Site Climate and Thermal Storage Systems

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Nicola Palestra ◽  
Giovanna Barigozzi ◽  
Antonio Perdichizzi
Keyword(s):  
Power Output ◽  
Parametric Analysis ◽  
Power Plants ◽  
Cooling System ◽  
Thermal Storage ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Air Cooling ◽  
Ambient Conditions ◽  
Cooling Systems

The paper presents the results of an investigation on inlet air cooling systems based on cool thermal storage, applied to combined cycle power plants. Such systems provide a significant increase of electric energy production in the peak hours; the charge of the cool thermal storage is performed instead during the night time. The inlet air cooling system also allows the plant to reduce power output dependence on ambient conditions. A 127MW combined cycle power plant operating in the Italian scenario is the object of this investigation. Two different technologies for cool thermal storage have been considered: ice harvester and stratified chilled water. To evaluate the performance of the combined cycle under different operating conditions, inlet cooling systems have been simulated with an in-house developed computational code. An economical analysis has been then performed. Different plant location sites have been considered, with the purpose to weigh up the influence of climatic conditions. Finally, a parametric analysis has been carried out in order to investigate how a variation of the thermal storage size affects the combined cycle performances and the investment profitability. It was found that both cool thermal storage technologies considered perform similarly in terms of gross extra production of energy. Despite this, the ice harvester shows higher parasitic load due to chillers consumptions. Warmer climates of the plant site resulted in a greater increase in the amount of operational hours than power output augmentation; investment profitability is different as well. Results of parametric analysis showed how important the size of inlet cooling storage may be for economical results.

Assessments of High-Efficient Regenerative Evaporative Cooler Effects on Desiccant Air Cooling Systems

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Hakan Caliskan ◽  
Dae-Young Lee ◽  
Hiki Hong
Keyword(s):  
Cooling System ◽  
Dew Point ◽  
Air Cooling ◽  
Sensible Heat ◽  
Cooling Systems ◽  
High Efficient ◽  
Air Cooling System ◽  
Evaporative Cooler ◽  
Effectiveness And Efficiency ◽  
And Performance

Abstract In this paper, the effects of regenerative evaporative coolers on the dry desiccant air cooling system are assessed. Thermodynamic analysis is performed point by point on the unmodified (ɛ = 0.67) and modified (ɛ = 1) regenerative evaporative cooler supported systems. It is found that the effectiveness and efficiency of the system were significantly increased by modification. Effectiveness of the system increases from 0.95 to 2.16 for the wet bulb and from 0.63 to 1.43 for dew point effectivenesses, while the exergy efficiency increases from 18.40% to 41.93%. Exergy and energy performances of the system increase 1.28 times and 0.61 times, respectively. Finally, sustainability is increased by 40% with the modification of the regenerative evaporative cooler. Also, changing the regenerative evaporative cooler of the solid desiccant wheel with the effective one can increase the overall system efficiency and performance without changing the sensible heat and desiccant wheels.

Relative Cooling: Part II — Design Considerations and Efficiency

2001 ◽  
Author(s):  
Sandu Constantin ◽  
Dan Brasoveanu
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Cooling System ◽  
High Reliability ◽  
Difficult Problem ◽  
Turbine Engines ◽  
Air Cooling ◽  
Gas Turbine Engines ◽  
Coolant Pump ◽  
Cooling Systems

Abstract Cooling systems with liquid for gas turbine engines that use the relative motion of the engine stator with respect to the rotor for actuating the coolant pump can be encapsulated within the engine rotor. In this manner, the difficult problem of sealing stator/rotor interfaces at high temperature, pressure and relative velocity is circumvented. A first generation of such cooling systems could be manufactured using existing technologies and would boost the thermal efficiency of gas turbine engines by more than 2% compared to recent designs that use advanced air-cooling methods. Later, relative cooling systems could increase the thermal efficiency of gas turbine engines by 8%–11% by boosting the temperatures at turbine inlet to stoichiometric levels and recovering most of the heat extracted from turbine during cooling. The appreciated high reliability of this cooling system will allow widespread use for aerospace propulsion.

Relative Cooling With Liquid for Gas Turbines: Part I — A Solution for Exceeding 2000 K at Turbine Inlet

2001 ◽  
Author(s):  
Sandu Constantin ◽  
Dan Brasoveanu
Keyword(s):  
Thermal Efficiency ◽  
Gas Turbines ◽  
Cooling System ◽  
Turbine Blades ◽  
Air Cooling ◽  
Liquid Cooling ◽  
Cooling Systems ◽  
Turbine Inlet ◽  
Cooling Methods ◽  
Current Operating

Abstract The thermal efficiency of gas turbines is critically dependent on the temperature of burnt gases at turbine inlet, the higher this temperature the higher the efficiency. Stochiometric combustion would provide maximum efficiency, but in the absence of an internal cooling system, turbine blades cannot tolerate gas temperatures that exceed 1300 K. Therefore, for this temperature, the thermal efficiency of turbine engine is 40% less than theoretical maximum. Conventional air-cooling techniques of turbine blades allow inlet temperatures of about 1500 K on current operating engines yielding thermal efficiency gains of about 6%. New designs, that incorporate advanced air-cooling methods allows inlet temperatures of 1750–1800 K, with a thermal efficiency gain of about 6% relative to current operating engines. This temperature is near the limit allowed by air-cooling systems. Turbine blades can be cooled with air taken from the compressor or with liquid. Cooling systems with air are easier to design but have a relatively low heat transfer capacity and reduce the efficiency of the engine. Some cooling systems with liquid rely on thermal gradients to promote re-circulation from the tip to the root of turbine blades. In this case, the flow and cooling of liquid are restricted. For best results, cooling systems with liquid should use a pump to re-circulate the coolant. In the past, designers tried to place this pump on the engine stator and therefore were unable to avoid high coolant losses because it is impossible to reliably seal the stator-rotor interface. Therefore it was assumed that cooling systems with liquid could not incorporate pumps. This is an unwarranted assumption as shown studying the system in a moving frame of reference that is linked to the rotor. Here is the crucial fact overlooked by previous designers. The relative motion of engine stator with respect to the rotor is sufficient to motivate a cooling pump. Both the pump and heat exchange system that is required to provide rapid cooling of liquid with cold ambient air, could be located within the rotor. Therefore, the entire cooling system can be encapsulated within the rotor and the sealing problem is circumvented. Compared to recent designs that use advanced air-cooling methods, such a liquid cooling system would increase the thermal efficiency by 8%–11% because the temperatures at turbine inlet can reach stoichiometric levels and most of the heat extracted from turbine during cooling is recuperated. The appreciated high reliability of the system will permit a large applicability in aerospace propulsion.

Analysis of Running Energy Consumption of Fresh Air Cooling Systems

Solar Energy ◽  
2005 ◽  
Author(s):  
Jianing Zhao ◽  
Jun Guo ◽  
Weimeng Sun
Keyword(s):  
Energy Consumption ◽  
Total Energy ◽  
Cooling System ◽  
Air Cooling ◽  
Total Energy Consumption ◽  
Cooling Systems ◽  
Variable Air Volume ◽  
Air Volume ◽  
Air System ◽  
Different Seasons

Utilization of renewable energy becomes more and more attractive and crucial for sustainable buildings. A cooling system, using outdoor fresh air and combining with the conventional all-air system or running along during different seasons, is discussed in this study. Running energy consumption of this system is analyzed by a mathematical model using the Genetic Algorithm (GA) combined with the traditional Lagrange method. To evaluate and apply this new system, energy consumption of the chiller unit, water and air sub-systems, as well as the total energy consumption of such a system is compared with that of the conventional all-air system. Consequently, the total energy consumption is selected as the criterion of energy efficiency. The results show that the cooling system bears considerably energy efficient, and that it reduces energy consumption at least 14% and 12%, compared with the constant air volume and variable air volume system, respectively.

Heat Recovery From Bottom Ash in Waste Fired Boilers: Status of Technologies and Thermal Performance Modeling

2013 ◽  
Author(s):  
Kaneesamkandi M. Zakariya
Keyword(s):  
Thermal Performance ◽  
Heat Recovery ◽  
Cooling System ◽  
Bottom Ash ◽  
Heat Content ◽  
Municipal Waste ◽  
Feed Water ◽  
Air Cooling ◽  
Cooling Systems ◽  
Bed Temperature

Bottom ash from Municipal Waste fired boilers have sufficient heat content and this can be used to pre-heat the boiler feed water or the combustion air. A study of the recent developments in this area is done with a focus on the air based cooling method. Modeling and simulation of the thermal performance of an air cooled ash cooling system is done with the help of Gambit/Fluent software. Among several methods of waste disposal, incineration of Municipal Waste is opted mainly due to its energy potential and specific advantages like high volume reduction ratio and convenience in plant location. However, the inherent fuel qualities that confront this method are its high moisture and ash content and the consequent low calorific values. The fuel bed temperature in stoker fired incineration systems can reach up to 1200K and a considerable part of this heat is wasted by way of ash sensible heat loss. The methods used for ash cooling include the water cooled ash screw system, the rolling cylinder ash cooler, fluidized bed ash cooler and the high strength steel belt ash cooler. In this study, the simulation of the performance of water based and air based ash cooling systems is done for a certain municipal waste fired boiler. The effect of the two methods on the overall boiler efficiency is studied. Comparison of results with that of a working system indicates that air cooling systems can be as efficient as the water cooled systems. With the help of this study, bottom ash heat recovery, especially for waste fired boilers, will be appreciated better and power plant designers will have a better insight into this area.

Privacy and trust in Facebook photo sharing: age and gender differences

2016 ◽  
Vol 50 (4) ◽  
pp. 462-480 ◽  
Author(s):  
Aqdas Malik ◽  
Kari Hiekkanen ◽  
Marko Nieminen
Keyword(s):  
Age Differences ◽  
Online Survey ◽  
Age Groups ◽  
Web Based ◽  
Content Type ◽  
Photo Sharing ◽  
Gender And Age ◽  
Significant Difference ◽  
Gender And Age Differences ◽  
And Gender

Purpose The purpose of this paper is to examine gender and age differences regarding various aspects of privacy, trust, and activity on one of the most popular Facebook activity – “photo sharing.” Design/methodology/approach The data were collected using an online survey hosted by a web-based survey service for three weeks during December 2014-January 2015. The target audience comprised of Facebook users over 18 years engaged in sharing their photos on the platform. Findings Women and young Facebook users are significantly more concerned about the privacy of their shared photos. Meanwhile, users from older age groups are less active in using the site, in sharing photos, and in taking privacy-related protective measures. Interestingly, despite having more privacy concerns, young Facebook users display higher trust levels toward the platform than older users. Overall, in the study, there was an extremely significant difference in privacy attitudes among people under and over 35 years of age. Originality/value The main contribution of this study is new knowledge regarding the gender and age differences in various privacy-related aspects, trust, and activity. Findings from the study broadens the overall understanding of how these issues positively/negatively influence the photo-sharing activity on Facebook.

scholarly journals Innovative Turbine Intake Air Cooling Systems and Their Rational Designing

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6201
Author(s):  
Andrii Radchenko ◽  
Eugeniy Trushliakov ◽  
Krzysztof Kosowski ◽  
Dariusz Mikielewicz ◽  
Mykola Radchenko
Keyword(s):  
Gas Turbines ◽  
Maximum Rate ◽  
Cooling System ◽  
Ambient Air ◽  
Cooling Capacity ◽  
Climatic Conditions ◽  
Air Cooling ◽  
Thermal Loads ◽  
Cooling Systems ◽  
Air Cooling System

The efficiency of cooling ambient air at the inlet of gas turbines in temperate climatic conditions was analyzed and reserves for its enhancing through deep cooling were revealed. A method of logical analysis of the actual operation efficiency of turbine intake air cooling systems in real varying environment, supplemented by the simplest numerical simulation was used to synthesize new solutions. As a result, a novel trend in engine intake air cooling to 7 or 10 °C in temperate climatic conditions by two-stage cooling in chillers of combined type, providing an annual fuel saving of practically 50%, surpasses its value gained due to traditional air cooling to about 15 °C in absorption lithium-bromide chiller of a simple cycle, and is proposed. On analyzing the actual efficiency of turbine intake air cooling system, the current changes in thermal loads on the system in response to varying ambient air parameters were taken into account and annual fuel reduction was considered to be a primary criterion, as an example. The improved methodology of the engine intake air cooling system designing based on the annual effect due to cooling was developed. It involves determining the optimal value of cooling capacity, providing the minimum system sizes at maximum rate of annual effect increment, and its rational value, providing a close to maximum annual effect without system oversizing at the second maximum rate of annual effect increment within the range beyond the first maximum rate. The rational value of design cooling capacity provides practically the maximum annual fuel saving but with the sizes of cooling systems reduced by 15 to 20% due to the correspondingly reduced design cooling capacity of the systems as compared with their values defined by traditional designing focused to cover current peaked short-term thermal loads. The optimal value of cooling capacity providing the minimum sizes of cooling system is very reasonable for applying the energy saving technologies, for instance, based on the thermal storage with accumulating excessive (not consumed) cooling capacities at lowered current thermal loads to cover the peak loads. The application of developed methodology enables revealing the thermal potential for enhancing the efficiency of any combustion engine (gas turbines and engines, internal combustion engines, etc.).

Design and Experimental Validation of a Shape Memory Alloy Actuator for Linear Motors

2015 ◽  
Vol 783 ◽  
pp. 69-75 ◽  
Author(s):  
Francesco Aggogeri ◽  
Nicola Pellegrini
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Experimental Validation ◽  
Closed Loop ◽  
Cooling System ◽  
Air Cooling ◽  
Cooling Systems ◽  
Linear Motors ◽  
Forced Air ◽  
The Mathematical Model

This paper presents an innovative mechanical actuator using a shape memory alloy (SMA) with a cooling system based on combined thermoelectric effect and forced air cooling systems. The main advantages of using SMAs include the reduction of the system weight, the ease and reliability in application, and a simple control strategy. This study focuses on the development of the system highlighting the mathematical model of the actuator, and an experimental prototype was implemented. Several experiments are used to validate the model and to identify best SMA actuator configuration parameters. Experiments were used to evaluate the actuator closed-loop performance, stability, and robustness properties.

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