scholarly journals Laboratory tests of a prototypical user-centric radiant cooling solution

2021 ◽  
Vol 2069 (1) ◽  
pp. 012122
Author(s):  
H Teufl ◽  
M Schuss ◽  
A Mahdavi
Keyword(s):  
Surface Temperature ◽  
Cooling System ◽  
Dew Point ◽  
Cooling Systems ◽  
Efficient Operation ◽  
Radiant Cooling ◽  
Close Proximity ◽  
Free Cooling ◽  
Condensed Water ◽  
Vapour Condensation

Abstract Radiant cooling systems are being increasingly promoted because of their energy efficient operation as well as their potential to improve occupants’ thermal comfort due to a draft-free cooling process. This paper focuses on a specific radiant cooling approach, which was introduced in previous contributions. This approach involves the positioning of relatively small-sized vertical radiant panels in the close proximity to occupants. Furthermore, the panels incorporate drainage systems or collection elements to accommodate, if needed, water vapour condensation. Consequently, the surface temperature of the radiant panels does not need to stay above the dew point temperature. We present the outcome of a preliminary experimental investigation of such a personal radiant cooling system. In this context, prototypical radiant panels were installed in a laboratory and multiple experiments were conducted. The uniformity level of the panels’ surface temperature distribution was documented. Moreover, near-panel air flow velocities were measured at several positions. Likewise, the formation of condensed water on panels was observed for different panel surface temperatures, room temperatures, and room humidity levels. The results of the preliminary laboratory investigation do not point to any risk of draft or turbulence discomfort.

Nocturnal Cooling of Water as Free Cooling Source for Building Indoor Radiant Cooling in Malaysian Climate

2016 ◽  
Vol 833 ◽  
pp. 94-101
Author(s):  
Muhammad Syukri Imran ◽  
Azhaili Baharun ◽  
Siti Halipah Ibrahim ◽  
Wan Azlan bin Wan Zainal Abidin
Keyword(s):  
Cooling System ◽  
Operating Temperature ◽  
Dew Point ◽  
Wave Radiation ◽  
Cooling Power ◽  
Test Model ◽  
Dew Point Temperature ◽  
Long Wave ◽  
Radiant Cooling ◽  
Free Cooling

Normally mechanical chiller supplies chill water temperature at a higher operating temperature to charge a radiant cooling system in building. Other source of cooling is possible since the operating temperature for radiant cooling is limited by the air dew point temperature. This study investigates cooling of water through long wave radiation to the night sky in Kuching Sarawak, Malaysia and utilise this water for radiant cooling purpose. Mathematical model were developed to predict the cooling power of the nocturnal cooling over typical metal roof and was compared to an experimental data. The measurement from the test model verified the predicted data and a yearly potential from nocturnal cooling in this region was established. The amount of cooled water generated from this night cooling system was also calculated. Results showed that an average of 73 W/m2 nocturnal cooling power is possible in this region.

scholarly journals Optimization of bioinspired triangular patterns for water condensation and transport

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190127 ◽  
Author(s):  
Dong Song ◽  
Bharat Bhushan
Keyword(s):  
Relative Humidity ◽  
Pressure Gradient ◽  
Surface Temperature ◽  
Dew Point ◽  
Laplace Pressure ◽  
Theme Issue ◽  
Water Condensation ◽  
Water Collection ◽  
Condensed Water ◽  
Droplet Condensation

Water condenses on a surface in ambient environment if the surface temperature is below the dew point. For water collection, droplets should be transported to storage before the condensed water evaporates. In this study, Laplace pressure gradient inspired by conical spines of cactus plants is used to facilitate the transport of water condensed in a triangular pattern to the storage. Droplet condensation, transportation and water collection rate within the bioinspired hydrophilic triangular patterns with various lengths and included angles, surrounded by superhydrophobic regions, were explored. The effect of relative humidity was also explored. This bioinspired technique can be used to develop efficient water collection systems. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

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.

scholarly journals Testing of a Radiant Wall Cooling System with Pipes Coupled to Aerated Blocks

2021 ◽  
Author(s):  
Martin Šimko ◽  
Dušan Petráš ◽  
Michal Krajčík ◽  
Daniel Szabó
Keyword(s):  
Surface Temperature ◽  
Cooling System ◽  
Thermal Response ◽  
Cooling Capacity ◽  
Climatic Conditions ◽  
Dew Point ◽  
Outdoor Environment ◽  
Design Parameters ◽  
Indoor Climate ◽  
Thermal Output

Thermal output, surface temperatures, and supply and return water temperature were measured for a wall cooling system involving pipe attached to a wall section made of thermally insulating blocks. The experiment was performed for warm climatic conditions typical of, e.g., summer in Central and Northern Europe. The outdoor environment was simulated by a climatic chamber while the indoor climate was simulated by attaching a hotbox to the wall surface. The sensitivity of thermal output to several design parameters was investigated by 2D numerical simulations. The measurements showed a fast thermal response of the wall system. The cooling output was 38.3 W per m2 of the cooling area which equalled about 4.8 W/m2 per 1 K temperature difference between water and hotbox. The lowest surface temperature of 19.6 °C was measured at the pipe. Thus, the cooling output could be enhanced by reducing the surface temperature closer to the dew point temperature. The temperature of water in the pipe was very close to the surface temperature. It was illustrated how this characteristic of the wall cooling system tested positively affects the efficiency and cooling capacity of an air-to-water heat pump.

scholarly journals A Study on the Energy Reduction Measures of Data Centers through Chilled Water Temperature Control and Water-Side Economizer

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3575
Author(s):  
Yu-Jin Kim ◽  
Ju-Wan Ha ◽  
Kyung-Soon Park ◽  
Young-Hak Song
Keyword(s):  
Energy Consumption ◽  
Water Temperature ◽  
Data Center ◽  
Cooling System ◽  
Water Control ◽  
Cooling Systems ◽  
Efficient Operation ◽  
Water Side ◽  
Chilled Water ◽  
Active Research

The degree of integration of IT devices and consumption of cooling energy are consistently increasing owing to developments in the data center industry. Hence, to ensure the smooth operation and fault prevention of IT devices, the energy consumption of cooling systems has increased, leading to active research on improvements in cooling system performance for reducing energy consumption. This study examines the reduction in cooling energy consumption using a simulation by applying chilled water control and a water-side economizer (WSE) system to enhance the cooling system efficiency. The simulation results showed that the energy consumption was reduced by 1.8% when the chilled water temperature was set to 11 °C in a conventional system and by up to 19.6% when WSE was also applied. Furthermore, when the changes in chilled water temperature were applied for efficient operation of WSE, the energy consumption was reduced by up to 30.1% compared to that in conventional energy systems.

scholarly journals Membrane-assisted radiant cooling for expanding thermal comfort zones globally without air conditioning

2020 ◽  
Vol 117 (35) ◽  
pp. 21162-21169 ◽  
Author(s):  
Eric Teitelbaum ◽  
Kian Wee Chen ◽  
Dorit Aviv ◽  
Kipp Bradford ◽  
Lea Ruefenacht ◽  
...  
Keyword(s):  
Water Supply ◽  
Thermal Comfort ◽  
Cooling System ◽  
Thermal Sensation ◽  
Dew Point ◽  
Mean Radiant Temperature ◽  
Radiation Exchange ◽  
Radiant Cooling ◽  
Chilled Water ◽  
Radiant Temperature

We present results of a radiant cooling system that made the hot and humid tropical climate of Singapore feel cool and comfortable. Thermal radiation exchange between occupants and surfaces in the built environment can augment thermal comfort. The lack of widespread commercial adoption of radiant-cooling technologies is due to two widely held views: 1) The low temperature required for radiant cooling in humid environments will form condensation; and 2) cold surfaces will still cool adjacent air via convection, limiting overall radiant-cooling effectiveness. This work directly challenges these views and provides proof-of-concept solutions examined for a transient thermal-comfort scenario. We constructed a demonstrative outdoor radiant-cooling pavilion in Singapore that used an infrared-transparent, low-density polyethylene membrane to provide radiant cooling at temperatures below the dew point. Test subjects who experienced the pavilion (n= 37) reported a “satisfactory” thermal sensation 79% of the time, despite experiencing 29.6 ± 0.9 °C air at 66.5 ± 5% relative humidity and with low air movement of 0.26 ± 0.18 m⋅s−1. Comfort was achieved with a coincident mean radiant temperature of 23.9 ± 0.8 °C, requiring a chilled water-supply temperature of 17.0 ± 1.8 °C. The pavilion operated successfully without any observed condensation on exposed surfaces, despite an observed dew-point temperature of 23.7 ± 0.7 °C. The coldest conditions observed without condensation used a chilled water-supply temperature 12.7 °C below the dew point, which resulted in a mean radiant temperature 3.6 °C below the dew point.

scholarly journals Simplified Building Thermal Model Used for Optimal Control of Radiant Cooling System

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Lei He ◽  
Bo Lei ◽  
Haiquan Bi ◽  
Tao Yu
Keyword(s):  
Supervisory Control ◽  
Thermal Model ◽  
Thermal Environment ◽  
Cooling System ◽  
Hvac Systems ◽  
Cooling Load ◽  
System Operation ◽  
Cooling Systems ◽  
Radiant Cooling ◽  
Cooling Loads

MPC has the ability to optimize the system operation parameters for energy conservation. Recently, it has been used in HVAC systems for saving energy, but there are very few applications in radiant cooling systems. To implement MPC in buildings with radiant terminals, the predictions of cooling load and thermal environment are indispensable. In this paper, a simplified thermal model is proposed for predicting cooling load and thermal environment in buildings with radiant floor. In this thermal model, the black-box model is introduced to derive the incident solar radiation, while the genetic algorithm is utilized to identify the parameters of the thermal model. In order to further validate this simplified thermal model, simulated results from TRNSYS are compared with those from this model and the deviation is evaluated based on coefficient of variation of root mean square (CV). The results show that the simplified model can predict the operative temperature with a CV lower than 1% and predict cooling loads with a CV lower than 10%. For the purpose of supervisory control in HVAC systems, this simplified RC thermal model has an acceptable accuracy and can be used for further MPC in buildings with radiation terminals.

scholarly journals Design and Analysis of Radiant Ceiling Cooling Panels for Classroom

2021 ◽  
Vol 9 (VI) ◽  
pp. 580-583
Author(s):  
Ms. Amruta Mohite
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Water Flow Rate ◽  
Specific Area ◽  
Paper Analysis ◽  
Cfd Analysis ◽  
Cooling Systems ◽  
Environment Friendly ◽  
Radiant Cooling ◽  
Study Case

In this study, radiant cooling panel is designed for a classroom. An arrangement is made such that the panels cover 70% of ceiling area. For study case a classroom is considered which need 27 such panels for covering 70% of area. The arrangement of panels, water flow rate, required temperature and amount of heat transfer taking place through panels is discussed in the paper. A cooling system is selected for maintaining the desired water temperature. Comparison is done between the cooling systems and the user can use any of them according to the requirements and cost. This system does not use any refrigerant hence it is environment friendly and can add a considerable solution to maintain temperature of a specific area. CFD analysis of the panel shows that adequate heat transfer takes place between panel and the room, this validates the design. When 15 ºC water is given as inlet to the panel, we get 22 ºC water as output at outlet of panel. In this paper, analysis is done for single panel same can be done for entire arrangement of panel structure.

scholarly journals An Overview of Different Indirect and Semi-Indirect Evaporative Cooling System for Study Potency of Nanopore Skinless Bamboo as An Evaporative Cooling New Porous Material

2020 ◽  
Vol 76 (3) ◽  
pp. 109-116
Author(s):  
Hendra Wijaksana ◽  
I. Nyoman Suprapta Winaya ◽  
Made Sucipta ◽  
Ainul Ghurri
Keyword(s):  
Energy Consumption ◽  
Porous Material ◽  
Cooling System ◽  
Evaporative Cooling ◽  
High Energy ◽  
Dew Point ◽  
Air Cooling ◽  
Cooling Systems ◽  
Evaporative Cooling System ◽  
Indirect Evaporative Cooling

The high energy consumption of compressor-based cooling system has prompted the researchers to study and develop non-compressor-based cooling system that less energy consumption, less environment damaging but still has high enough cooling performances. Indirect and semi indirect evaporative cooling system is the feasible non-compressor-based cooling systems that can reach the cooling performance required. These two evaporative cooling systems has some different in construction, porous material used, airflow scheme and secondary air-cooling method used for various applications. This paper would report the cooling performances achieved by those two-cooling systems in terms of cooling efficiency, cooling capacity, wet bulb effectiveness, dew point effectiveness, and temperature drop. Porous material used in indirect and semi-indirect evaporative cooling would be highlighted in terms of their type, size, thickness and any other feature. The introduction of nanopore skinless bamboo potency as a new porous material for either indirect or semi-indirect evaporative cooling would be described. In the future study of nanopore skinless bamboo, a surface morphology and several hygrothermal test including sorption, water vapor transmission, thermal conductivity test would be applied, before it utilizes as a new porous material for direct or semi indirect evaporative cooling.

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