scholarly journals The Energy Performances of a Ground-to-Air Heat Exchanger: A Comparison Among Köppen Climatic Areas

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2895 ◽  
Author(s):  
Diana D’Agostino ◽  
Francesco Esposito ◽  
Adriana Greco ◽  
Claudia Masselli ◽  
Francesco Minichiello
Keyword(s):  
Heat Exchanger ◽  
Rio De Janeiro ◽  
Thermal Power ◽  
Volumetric Flow Rate ◽  
Power Reduction ◽  
Outlet Temperature ◽  
Hvac System ◽  
Pipe Length ◽  
Pre Treatment ◽  
Cooling Coils

In this paper the energy performances carried out by an investigation conducted on a Heating, Ventilation and Air Conditioning (HVAC) system, composed by an Air Handling Unit (AHU) for the primary air coupled with a horizontal-pipes Ground-to-Air Heat eXchanger (GAHX) and fan-coil units, for an office building, supposed to be placed in four different cities (Rio de Janeiro, Dubai, Naples, Ottawa) belonging to four different worldwide climatic areas, according to the Köppen climate classification. The investigation is performed by means of a two dimensional numerical model, experimentally validated, of an GAHX solved with finite element method. The results introduced in this paper are carried out by varying the length of the pipes and the air flow velocity; thus, also the number of tubes forming the GAHX is varied since the volumetric flow rate to be provided to the AHU must be kept constant. The energy performances of the above-mentioned HVAC system are analyzed, both in summer and in winter operation modes. Specifically, the reduction of the power of the heating and cooling coils in the AHU due to the pre-treatment of the air operated by the GAHX, the efficiency of the GAHX and the inlet-outlet temperature span are evaluated through a sensitivity analysis. These results lead to say that an GAHX for the geothermal pre-treatment of the air to be introduced into the AHU is energetically very convenient since it leads total thermal power savings in all the investigated cities, that makes this solution competitive. Specifically the best value of power reduction (61.5%) for a 100 m pipe-length GAHX is obtained in Ottawa, a city belonging to continental climate zone. The worst results in terms of power reduction are registered in Rio de Janeiro, a city belonging to the tropical or equatorial climates: this reduction, for a 100 m pipe-length ground to air heat exchanger, is 23.9%.

scholarly journals The Effect of Dry and Wet Bulb Temperature Variation on the Performance of the Indirect Evaporative Cooler

2019 ◽  
Vol 26 (4) ◽  
pp. 8-15
Author(s):  
Maki Zaidan ◽  
Fayadh Abed ◽  
Ali Farhad
Keyword(s):  
Heat Exchanger ◽  
Environmental Changes ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Computer Software ◽  
Volumetric Flow Rate ◽  
Weather Conditions ◽  
Centrifugal Fan ◽  
Pipe Length ◽  
Evaporative Cooling System

The research is about designing and building up an evaporative cooling system, working by two- stages evaporative cooling system using outer air (pure air). The system is founded by designing and making a heat exchanger of orthogonal flow from Aluminum sheets of (30*60*40) cm, which represents the first stage of the system (indirect stage). The second stage (direct stage) of the system is represented by making an equipment of air washing (cylindrical) with (45 height, 60 width, 3 thickness) cm. The cooling system pulls outer air by a Centrifugal fan. The air passes through the heat exchanger pipes to be cooled tangibly (without moistening). Then it goes over the equipment of air washing to be cooled and cools the specified space. Computer software was designed by FORTRAN Language (FORTRAN 90) to predict the evaporative air cooler performance to know the proper environmental and design conditions of the system. Some variables were made to study their effect on the thermal performance of the system. The studied variable is to change the volumetric flow rate of air from (750 cfm) to (2000 cfm) of the dry side, and from (750 cfm) to (2500 cfm) of the wet side. The pipe length was changed from (20 cm) to (45 cm), and its diameter from (0.5 cm) to (3 cm). Those were the design changes. On the environmental changes, we studied the effect of changing the temperature on the dry or wet bulb of the system. The study is taken place in Tikrit University (34. 35N; 43.37 E), to determine the suitability of the weather conditions of the region for the work of the system. It was taken place in the late August for two consecutive days, with readings of 24 hours. The results show that the best quantity of the air supplied, which represent the best performance of the system (750 cfm) and (1000 cfm) for the wet side when the diameter (1-1.5 cm) and length is (45 cm). The results show also the possibility of the work of this system for the region mentioned because it is characterized by its hot and dry climate in the summer, as the efficiency of evaporative evaporator increases the hot and dry environment by 80%.

scholarly journals A New Device Hypothesis for Water Extraction from Air and Basic Air Condition System in Developing Countries

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4507
Author(s):  
Paolo Maria Congedo ◽  
Cristina Baglivo ◽  
Giulia Negro
Keyword(s):  
Heat Pumps ◽  
Outlet Temperature ◽  
Water Recovery ◽  
African City ◽  
Photovoltaic Panel ◽  
Water Storage Tank ◽  
New Device ◽  
Mixing Chamber ◽  
Air Handling Units ◽  
Pre Treatment

This work proposes a new device for air treatment with dehumidification and water recovery/storage, with possible mitigation of indoor environmental conditions. The system is based on Peltier cells coupled with a horizontal earth-to-air heat exchanger, it is proposed as an easy-to-implement alternative to the heat pumps and air handling units currently used on the market, in terms of cost, ease of installation, and maintenance. The process provides the water collection from the cooling of warm-humid air through a process that leads to condensation and water vapor separation. The airflow generated by a fan splits into two dual flows that lap the two surfaces of the Peltier cells, one flow laps the cold surfaces undergoing sensible, latent cooling with dehumidification; the other flow laps the hot surfaces and heats up. The airflow undergoes thermal pre-treatment through the underground horizontal geothermal pipe that precedes the Peltier cells. In the water storage tank, which also works as a mixing chamber, the two air streams are mixed to regulate the outlet temperature. The system can be stand-alone if equipped with a photovoltaic panel and a micro wind turbine, able to be used in places where electricity is absent. The system, with different configurations, is modeled in the African city Kigali, in Rwanda.

scholarly journals An assessment of atmospheric deposition of metals and the physico -chemical parameters of a rainwater harvesting system in Rio de Janeiro Brazil, by means of statistical multivariate analysis

2020 ◽  
Vol 15 (4) ◽  
pp. 1
Author(s):  
Gabrielle Nunes da Silva ◽  
Letícia Delduque Alves ◽  
Isabella Escobar dos Santos ◽  
Daniele Maia Bila ◽  
Alfredo Akira Ohnuma Júnior ◽  
...  
Keyword(s):  
Rio De Janeiro ◽  
Fine Particles ◽  
Rainwater Harvesting ◽  
Principal Component ◽  
Hierarchical Cluster ◽  
High Concentration ◽  
Physico Chemical ◽  
Pearson Coefficient ◽  
Coefficient Corrélation ◽  
Pre Treatment

This study evaluates the rainwater harvesting system to determine the chemical quality of the water and allocate it for use. Samples were collected in the city of Rio de Janeiro at the points of Direct Precipitation (DP), First Flush (FF) and Reservoir (RR). The methodology involved carrying out an analysis of Ca, Cd, Cu, Na, Ni, Fe, K, Mg, Pb, Zn, conductivity, turbidity, pH and chloride. The R language was used for the principal component analysis, Pearson coefficient correlation, hierarchical cluster analysis, Tukey test and boxplot. The results show that when there is no interference from the catchment surface (DP), the rainwater has a low concentration of metals, although the first millimeters of rain have a concentration above what is permissible in the guidelines issued by the Ministry of Health (Ordinance n° 05/2017). The disposal system (FF) reduced the concentration of pollutants in the RR, but not enough to comply with legislation. It was noted that Ca, K and Na are the main metals found in rainwater. During the dry period, there were significant correlations between the physico-chemical and meteorological parameters. The high concentration of metals in the wet period suggests that rain assists the cleaning of the atmosphere and that most metals are present in the form of aerosols or fine particles suspended in the air. The findings reveal significant indications of acid rain and pre-treatment is recommended to ensure rainwater can be used safely for more mundane purposes.

On-Line Fuzzy Logic Temperature Control of a Concentric-Tubes Heat Exchanger Facility

2006 ◽  
Author(s):  
Claudia Ruiz-Mercado ◽  
Arturo Pacheco-Vega ◽  
Kevin Peters
Keyword(s):  
Heat Exchanger ◽  
Temperature Control ◽  
Fuzzy Controller ◽  
Fuzzy Rule ◽  
Outlet Temperature ◽  
Single Input Single Output ◽  
Single Output ◽  
On Line ◽  
The Difference ◽  
Two Stages

We develop a fuzzy rule based controller to perform on-line temperature control of a concentric-tubes heat exchanger facility. The rules were derived from dynamical values of the mass flow rates and fluid temperatures in the heat exchanger. The controller was embedded in a closed-loop single-input single-output system to control the outlet temperature of the cold fluid. The controller was constructed in two stages, the difference between them being the amount of information provided to the controller. To validate the fuzzy controller two sets of tests were carried out for maintaining a constant value of the outlet temperature under different perturbations. Results from this analysis demonstrate that the fuzzy-based controller is able to achieve control of the system, and that the information about the system provided to it is important in terms of accuracy and efficiency.

Performance Evaluation of a Vertical U-Tube Ground Heat Exchanger Using a Numerical Simulation Approach

2013 ◽  
Vol 724-725 ◽  
pp. 909-915
Author(s):  
Ping Fang Hu ◽  
Zhong Yi Yu ◽  
Fei Lei ◽  
Na Zhu ◽  
Qi Ming Sun ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Performance Evaluation ◽  
Heat Exchanger ◽  
Heat Pump ◽  
Heat Transfer Process ◽  
Working Fluid ◽  
Outlet Temperature ◽  
Ground Heat Exchanger ◽  
Ground Source Heat Pump ◽  
Ground Source

A vertical U-tube ground heat exchanger can be utilized to exchange heat with the soil in ground source heat pump systems. The outlet temperature of the working fluid through the U-tube not only accounts for heat transfer capacity of a ground heat exchanger, but also greatly affects the operational efficiency of heat pump units, which is an important characteristic parameter of heat transfer process. It is quantified by defining a thermal effectiveness coefficient. The performance evaluation is performed with a three dimensional numerical model using a finite volume technique. A dynamic simulation was conducted to analyze the thermal effectiveness as a function of soil thermal properties, backfill material properties, separation distance between the two tube legs, borehole depth and flow velocity of the working fluid. The influence of important characteristic parameters on the heat transfer performance of vertical U-tube ground heat exchangers is investigated, which may provide the references for the design of ground source heat pump systems in practice.

scholarly journals Evaluation of Energy Efficiency and the Reduction of Atmospheric Emissions by Generating Electricity from a Solar Thermal Power Generation Plant

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 645
Author(s):  
Gary Ampuño ◽  
Juan Lata-Garcia ◽  
Francisco Jurado
Keyword(s):  
Power Plants ◽  
New Technologies ◽  
Thermal Power ◽  
Energy Generation ◽  
Solar Thermal ◽  
Electrical Network ◽  
Climatic Data ◽  
Outlet Temperature ◽  
Solar Thermal Energy ◽  
Generation Plant

The increase of renewable energy generation to change the productivity of a country and electrify isolated sectors are some of the priorities that several governments have imposed in the medium term. Research centers are looking for new technologies to optimize the use of renewable energies and incorporate them into hybrid generation systems. In the present work, the modeling of a solar thermal energy generation plant is being carried out. The climatic data used belong to two coastal cities and one island of Ecuador. The contribution of this work is to simulate a complete model of SCF and PCS, in which the variables of outlet temperature and oil flow are involved at the same time. Previously investigations use only outlet temperature for evaluating power plants. The model of the solar thermal plant is composed of a field of solar collectors, a storage tank, and an energy conversion system. As a result, we obtain a model of a thermosolar plant that will allow us to make decisions when considering the incorporation of micronetworks in systems isolated from the electrical network. The use of thermosolar technology allows the reduction in the risk of spills by the transport of fossil fuels in ships. The study of the CO2 emission factor in Ecuador from 2011 to 2018 is also carried out.

scholarly journals The Effect of Flowrate and Effectiveness on Theoretical Design and Thermal Characteristic of a GHE

2018 ◽  
Vol 225 ◽  
pp. 01023
Author(s):  
T.M. Yusof ◽  
M.F. Basrawi ◽  
A. Shahrani ◽  
H. Ibrahim
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Thermal Characteristic ◽  
Variable Parameter ◽  
Cross Flow ◽  
Outlet Temperature ◽  
Performance Study ◽  
Commercial Unit ◽  
Hot Climate ◽  
Flow Heat

Ground heat exchanger is an exciting technique to reduce energy consumption in building especially in hot climate countries. Implementation of GHE for commercial unit in Malaysia is almost none in record. Thus, performance study of the GHE in Malaysia is crucial to be conducted either experimentally or numerically. Therefore, this paper presents the performance of GHE in term of effectiveness, outlet temperature and rate of heat transfer based on mathematical model. The model is developed based on cross flow heat exchanger with one fluid unmixed. There are two variable parameter used in the analysis which is effectiveness and flowrate of the air for 25 meter length of a PVC pipe. Three effectiveness values which is 0.8, 0.9 and 0.99 have been analysed in this study. Meanwhile, flowrate of air is ranging from 0.02 to 0.2 kg/s. Results show that flowrate at 0.02 kg/s gives great temperature reduction in the pipe compared with higher flowrate. However, flowrate of 0.2 kg/s produces higher cooling potential. Characteristic of the GHE for the rate of heat transfer with 80, 90 and 99 percent effectiveness also have been developed and it has been found that effectiveness of 0.9 provide good combination between flowrate and the rate of heat transfer for 25 meter length of the pipe

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