The Magnitude of the Thermal Energy Stored in a Building Wall Adjacent to an Unglazed Transpired Solar Collector

2011 ◽  
Author(s):  
Saeed Moaveni ◽  
Patrick A. Tebbe ◽  
Louis Schwartzkopf ◽  
Joseph Dobmeier ◽  
Joseph Gehrke ◽  
...  
Keyword(s):  
Air Temperature ◽  
Thermal Energy ◽  
Solar Collector ◽  
Hvac Systems ◽  
Volume Flow ◽  
Flow Rates ◽  
The Past ◽  
Building Wall ◽  
Collector Efficiency ◽  
Metal Wall

In this paper, we will present a method for estimating the stored thermal energy in a building wall that is adjacent to an unglazed transpired collector. We also discuss how this value should be incorporated in the collector efficiency calculations. An unglazed transpired collector is made of a relatively thin, dark, perforated metal wall that is installed approximately 14 inches (35.5 cm) away from a south facing building wall to create an enclosed plenum. Typically, the outside air is drawn into the collector by fans that are located on the top of the collector. These types of solar collectors are used to preheat the intake air using solar energy before the air enters existing HVAC systems. They are generally used in situations and buildings where large ventilation volume flow rates are required. Most of the studies related to unglazed transpired collectors deal with estimation of air temperature rise due to solar gain and recaptured heat loss from the adjoining building wall. In the past, studies have neglected the amount of thermal energy that is stored in the building wall. However, as shown in this study, the stored thermal energy is of significant amount, and if incorporated correctly in the collector efficiency calculations, it would lead to higher efficiency values.

Improving the Efficiency of DASC by Adding CeO2/CUO Hybrid Nanoparticles in Water

2018 ◽  
Vol 24 (8) ◽  
pp. 5651-5656
Author(s):  
V. Midhun Mohan ◽  
A. M Sajeeb
Keyword(s):  
Flow Rate ◽  
Solar Collector ◽  
Cuo Nanoparticles ◽  
Hybrid Nanoparticles ◽  
Direct Absorption ◽  
Flow Rates ◽  
The Past ◽  
Hybrid Combination ◽  
Collector Efficiency ◽  
Direct Absorption Solar Collector

Solar energy is the abundantly available source of renewable energy with least impact on environment. Direct absorption solar collector (DASC) is the commonly used device to absorb heat directly from sun and make use of it for different heating applications. In the past, many experiments have been done to increase the efficiency of DASC using nanofluids. In this paper, an examination of solar collector efficiency for hybrid CeO2/CuO-water (0.1% by volume) nanofluid under various flow rates and proportions of CeO2/CUO nanoparticles is investigated. The experiments were conducted at flow rates spanning from 20 cc/min to 100 cc/min and with CeO2/CUO nanoparticles proportions of 1:0, 1:0.5, 1:1, 0.5:1, and 0:1. The efficiency increases from 16.5% to 51.6% when the flow rate is increased from 20 cc/min to 100 cc/min for hybrid CeO2/CuO(1:1)-water nanofluid. The results also showed an increase in efficiency of 13.8, 18.1, 24.3, 24.9 and 26.1% with hybrid combination of CeO2/CUO at ratios 1:0, 1:0.5, 1:1, 0.5:1, and 0:1 respectively in comparison with water at a flow rate of 100 cc/min.

Improving the Efficiency of DASC by Adding CeO2/CuO Hybrid Nanoparticles in Water

2017 ◽  
Vol 17 (01n02) ◽  
pp. 1760011 ◽  
Author(s):  
V. Midhun Mohan ◽  
A. M. Sajeeb
Keyword(s):  
Flow Rate ◽  
Solar Collector ◽  
Cuo Nanoparticles ◽  
Hybrid Nanoparticles ◽  
Direct Absorption ◽  
Flow Rates ◽  
The Past ◽  
Hybrid Combination ◽  
Collector Efficiency ◽  
Direct Absorption Solar Collector

Solar energy is the abundantly available source of renewable energy with least impact on environment. Direct absorption solar collector (DASC) is the commonly used device to absorb heat directly from sun and make use of it for different heating applications. In the past, many experiments have been done to increase the efficiency of DASC using nanofluids. In this paper, an examination of solar collector efficiency for hybrid CeO2/CuO–water (0.1% by volume) nanofluid under various flow rates and proportions of CeO2/CuO nanoparticles is investigated. The experiments were conducted at flow rates spanning from 20[Formula: see text]cc/min to 100[Formula: see text]cc/min and with CeO2/CuO nanoparticles proportions of 1:0, 1:0.5, 1:1, 0.5:1 and 0:1. The efficiency increases from 16.5% to 51.6% when the flow rate is increased from 20[Formula: see text]cc/min to 100[Formula: see text]cc/min for hybrid CeO2/CuO (1:1)–water nanofluid. The results also showed an increase in efficiency of 13.8%, 18.1%, 24.3%, 24.9% and 26.1% with hybrid combination of CeO2/CuO at ratios 1:0, 1:0.5, 1:1, 0.5:1 and 0:1, respectively, in comparison with water at a flow rate of 100[Formula: see text]cc/min.

A Numerical Model for Thermal Performance of an Unglazed Transpired Solar Collector

2011 ◽  
Author(s):  
Saeed Moaveni ◽  
Patrick A. Tebbe ◽  
Louis Schwartzkopf ◽  
Joseph Dobmeier ◽  
Joseph Gehrke ◽  
...  
Keyword(s):  
Numerical Model ◽  
Air Temperature ◽  
Thermal Performance ◽  
Solar Collector ◽  
Energy Savings ◽  
Ambient Air ◽  
Solar Collectors ◽  
Heating Unit ◽  
Plate Temperature ◽  
Building Wall

In this paper, we will present a numerical model for estimating the thermal performance of unglazed transpired solar collectors located on the Breck School campus in Minneapolis, Minnesota. The solar collectors are installed adjacent to the southeast facing wall of a field house. The collectors preheat the intake air before entering the primary heating unit. The solar collector consists of 8 separate panels (absorber plates). Four fans are connected to the plenum that is created by the absorber plates and the adjoining field house wall. All fresh air for the field house is provided by the solar collectors before being filtered and heated by four, independent two stage natural gas fired heaters. Moreover, the following data were collected onsite using a data acquisition system: indoor field house space temperature, ambient air temperature, wind speed, wind direction, the plenum exit air temperature, the absorber plate temperature, and the air temperatures inside the plenum. The energy balance equations for the collector, the adjacent building wall, and the plenum are formulated. The numerical model is used to predict the air temperature rise inside the plenum, recaptured heat loss from the adjoining building wall, energy savings, and the efficiency of the collectors. The results of the numerical model are then compared to the results obtained from the onsite measurements; which are in good agreement. The model presented in this paper is simple yet accurate enough for architects and engineers to use it with ease to predict the thermal performance of a collector.

Performance Evaluation of a New Type of Combined Photovoltaic–Thermal Solar Collector

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Gianpiero Colangelo ◽  
Danilo Romano ◽  
Giuseppe Marco Tina
Keyword(s):  
Thermal Analysis ◽  
Performance Evaluation ◽  
Water Flow ◽  
Thermal Energy ◽  
Solar Collector ◽  
High Water ◽  
Solar Panel ◽  
Flow Rates ◽  
New Type ◽  
Panel Design

A thermal analysis of a new photovoltaic–thermal (PV–T) solar panel design, called thermal electric solar panel integration (TESPI), has been performed using radtherm thermoanalitics software. Combinations of different water flow rates and different panel configurations have been analyzed to determine which one produces best performance in terms of optimal PV efficiency and available thermal energy. Higher total panel efficiencies (thermal and electrical) were achieved in configurations utilizing the highest water flow rates, independently from the chosen configuration. However, high water flow rates translated into minimal net temperature differences between the PV/T panel inlet and outlet.

Assessment of the Use of Humidified Nasal Cannulas for Oxygen Therapy in Patients with Epistaxis

ORL ◽  
2021 ◽  
pp. 1-5
Author(s):  
Jingjing Liu ◽  
Tengfang Chen ◽  
Zhenggang Lv ◽  
Dezhong Wu
Keyword(s):  
Flow Rate ◽  
Oxygen Therapy ◽  
Preliminary Investigation ◽  
Nasal Cannula ◽  
Low Flow ◽  
Antiplatelet Drugs ◽  
Flow Rates ◽  
The Past ◽  
Oxygen Inhalation ◽  
Significant Difference

<b><i>Introduction:</i></b> In China, nasal cannula oxygen therapy is typically humidified. However, it is difficult to decide whether to suspend nasal cannula oxygen inhalation after the nosebleed has temporarily stopped. Therefore, we conducted a preliminary investigation on whether the use of humidified nasal cannulas in our hospital increases the incidence of epistaxis. <b><i>Methods:</i></b> We conducted a survey of 176,058 inpatients in our hospital and other city branches of our hospital over the past 3 years and obtained information concerning their use of humidified nasal cannulas for oxygen inhalation, nonhumidified nasal cannulas, anticoagulant and antiplatelet drugs, and oxygen inhalation flow rates. This information was compared with the data collected at consultation for epistaxis during these 3 years. <b><i>Results:</i></b> No significant difference was found between inpatients with humidified nasal cannulas and those without nasal cannula oxygen therapy in the incidence of consultations due to epistaxis (χ<sup>2</sup> = 1.007, <i>p</i> &#x3e; 0.05). The same trend was observed among hospitalized patients using anticoagulant and antiplatelet drugs (χ<sup>2</sup> = 2.082, <i>p</i> &#x3e; 0.05). Among the patients with an inhaled oxygen flow rate ≥5 L/min, the incidence of ear-nose-throat (ENT) consultations due to epistaxis was 0. No statistically significant difference was found between inpatients with a humidified oxygen inhalation flow rate &#x3c;5 L/min and those without nasal cannula oxygen therapy in the incidence of ENT consultations due to epistaxis (χ<sup>2</sup> = 0.838, <i>p</i> &#x3e; 0.05). A statistically significant difference was observed in the incidence of ENT consultations due to epistaxis between the low-flow nonhumidified nasal cannula and nonnasal cannula oxygen inhalation groups (χ<sup>2</sup> = 18.428, <i>p</i> &#x3c; 0.001). The same trend was observed between the 2 groups of low-flow humidified and low-flow nonhumidified nasal cannula oxygen inhalation (χ<sup>2</sup> = 26.194, <i>p</i> &#x3c; 0.001). <b><i>Discussion/Conclusion:</i></b> Neither high-flow humidified nasal cannula oxygen inhalation nor low-flow humidified nasal cannula oxygen inhalation will increase the incidence of recurrent or serious epistaxis complications; the same trend was observed for patients who use anticoagulant and antiplatelet drugs. Humidification during low-flow nasal cannula oxygen inhalation can prevent severe and repeated epistaxis to a certain extent.

RENAL RESEARCH INSTITUTE SYMPOSIUM: Effective Diffusion Volume Flow Rates (Qe) for Urea, Creatinine, and Inorganic Phosphorous (Qeu, Qecr, QeiP) During Hemodialysis

2003 ◽  
Vol 16 (6) ◽  
pp. 474-476 ◽  
Author(s):  
Frank A. Gotch ◽  
Froilan Panlilio ◽  
Olga Sergeyeva ◽  
Laura Rosales ◽  
Tom Folden ◽  
...  
Keyword(s):  
Effective Diffusion ◽  
Volume Flow ◽  
Flow Rates ◽  
Inorganic Phosphorous ◽  
Research Institute

Performance of Large-Scale Seasonal Thermal Energy Stores

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
F. Ochs ◽  
W. Heidemann ◽  
H. Müller-Steinhagen
Keyword(s):  
Thermal Energy ◽  
Large Scale ◽  
Fossil Fuels ◽  
Waste Heat ◽  
Type System ◽  
Solar Thermal Energy ◽  
Construction Costs ◽  
The Past ◽  
Energy Stores ◽  
Construction Type

More than 30 international research and pilot seasonal thermal energy stores (TESs) were realized within the past 30 years. Experiences with operation of these systems show that TES are technically feasible and work well. Seasonal storage of solar thermal energy or of waste heat from heat and power cogeneration plants can significantly contribute to substitute fossil fuels in future energy systems. However, performance with respect to thermal losses and lifetime has to be enhanced, while construction costs have to be further reduced. This paper gives an overview about the state-of-the-art of seasonal thermal energy storage with the focus on tank and pit TES construction. Aspects of TES modeling are given. Based on modeled and measured data, the influence of construction type, system configuration, and boundary conditions on thermal losses of large-scale TES is identified. The focus is on large-scale applications with tank and pit thermal energy stores and on recent investigations on suitable materials and constructions. Furthermore, experiences with the operation of these systems with respect to storage performance are discussed.

Experimental and Theoretical Investigation of Performance of a Solar Chimney Model, Part I: Experimental Investigation

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Essaied M Shuia ◽  
Bashir H Arebi ◽  
Ibrahim A abuashe
Keyword(s):  
Experimental Data ◽  
Wind Speed ◽  
Solar Radiation ◽  
Air Temperature ◽  
Solar Collector ◽  
Experimental Results ◽  
Internal Diameter ◽  
Solar Chimney ◽  
Air Velocity ◽  
Collector Temperature

This paper presents the experimental data that was collected from small pilot solar chimney. The experimental data together with ambient conditions are used to evaluate the performance and study the behavior of the solar chimney; this data will be used for comparison with theoretical models in another paper [part II). The solar chimney prototype was designed and constructed at the Subrata Faculty of Engineering-Libya. The data were collected over several days of June 2011. The solar chimney system contains two main components; the solar collector and the solar chimney. The solar collector root‘ has a circular area of126 m3, the solar chimney is a PVC tube with internal diameter of 0.2 m and the total height of chimney is 9.3 m. The measurements include the intensity of solar radiation inside/outside the collector, temperature and velocity of air at the entrance of the chimney, temperature and speed of wind outside the collector, temperature of the ground inside collector al1d temperature measurements of air at speci?c points at different levels throughout the collector. Solar irradiance was found to affect the chimney temperature and subsequently affects chimney air velocity. The experimental results showed that temperature differences of (30 - 45°C) were recorded between the ambient temperature and that of air inside the chimney in the middle of the day, where the highest air temperature of 73.4°C was recorded at the entrance of the solar chimney. The maximum air velocity of 3.6 m/s was recorded inside the solar chimney at noon on 9 June. Wind speed outside the collector had a small effect on the speed of the air inside the chimney and tends to change slightly, hence, can neglect influence of wind speed on the performance of the system. Also the experimental results indicate that such type of system can trap a suf?cient amount of solar radiation, which elevates the air temperature to a suf?cient value able to generate enough air ?ow to operate a wind turbine to produce electricity; this means the solar chimney system for electricity production can work in the north-western part of Libya in the summer time at least.

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