scholarly journals Simulation of a Solar-Assisted Air-Conditioning System Applied to a Remote School

2019 ◽  
Vol 9 (16) ◽  
pp. 3398 ◽  
Author(s):  
Jesús Armando Aguilar-Jiménez ◽  
Nicolás Velázquez ◽  
Ricardo López-Zavala ◽  
Luis A. González-Uribe ◽  
Ricardo Beltrán ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Thermal Energy ◽  
Cooling Tower ◽  
Cooling System ◽  
Maximum Load ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Solar Thermal Energy ◽  
Heating And Cooling ◽  
Cooling Coils

In this work, we present an absorption cooling system with 35 kW capacity driven by solar thermal energy, installed in the school of Puertecitos, Mexico, an off-grid community with a high level of social marginalization. The cooling system provides thermal comfort to the school’s classrooms through four 8.75-kW cooling coils, while a 110-m2 field of evacuated tube solar collectors delivers the thermal energy needed to activate the cooling machine. The characteristics of the equipment installed in the school were used for simulation and operative analysis of the system under the influence of typical factors of an isolated coastal community, such as the influence of climate, thermal load, and water consumption in the cooling tower, among others. The aim of this simulation study was to determine the best operating conditions prior to system start-up, to establish the requirements for external heating and cooling services, and to quantify the freshwater requirements for the proper functioning of the system. The results show that, with the simulated strategies implemented, with a maximum load operation, the system can maintain thermal comfort in the classrooms for five days of classes. This is feasible as long as weekends are dedicated to raising the water temperature in the thermal storage tank. As the total capacity of the system is distributed in the four cooling coils, it is possible to control the cooling demand in order to extend the operation periods. Utilizing 75% or less of the cooling capacity, the system can operate continuously, taking advantage of stored energy. The cooling tower requires about 750 kg of water per day, which becomes critical given the scarcity of this resource in the community.

A System Modeling Approach for Active Solar Heating and Cooling System With Phase Change Material (PCM) for Small Buildings

2012 ◽  
Author(s):  
Rajeevan Ratnanandan ◽  
Jorge E. González
Keyword(s):  
Phase Change ◽  
Thermal Energy ◽  
Cooling System ◽  
Hot Water ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Adsorption Chiller ◽  
Heating And Cooling ◽  
Solar Thermal Collectors ◽  
Change Material

The paper presents a study of the performance of an active solar thermal heating and cooling system for small buildings. The work is motivated by the need for finding sustainable alternatives for building applications that are climate adaptable. The energy demand for heating and cooling needs in residential and light commercial buildings in mid-latitudes represent more than 50% of the energy consumed annually by these buildings. Solar thermal energy represents an untapped opportunity to address this challenge with sustainable solutions. Direct heating could be a source for space heating and hot water, and for heat operated cooling systems to provide space cooling. However, a key limitation in mainstreaming solar thermal for heating and cooling has been the size of thermal storage to implement related technologies. We address this issue by coupling a Phase Change Material (PCM) with an adsorption chiller and a radiant flooring system for year round solar thermal energy utilization in Northern climates. The adsorption chiller allows for chill water production driven by low temperature solar thermal energy for summer cooling, and low temperature radiant heating provides for space heating in winter conditions, while hot water demand is supplied year round. These active systems are operated by high performance solar thermal collectors. The PCM has been selected to match temperatures requirements of the adsorption chiller, and the tank was designed to provide three levels of temperatures for all applications; cooling, heating, and hot water. The material selection is paraffin sandwiched with a graphite matrix to increase the conductivity. The specific objective of the preset work is to provide a system optimization of this active system. The system is represented by a series of mathematical models for each component; PCM tank with heat exchangers, the adsorption machine, the radiant floor, and the solar thermal collectors (Evacuated tubular collectors). The PCM modeling allows for sensible heating, phase change process, and superheating. Parametric simulations are conducted for a defined small building in different locations in US with the objective of defining design parameters for; optimal solar collector array, sizing of the PCM tank, and performance of the adsorption machine and radiant heating system. The monthly and annual solar fractions of the system are also reported.

Numerical Studies on the Performance of a Bubble Pump

2013 ◽  
Vol 330 ◽  
pp. 203-208 ◽  
Author(s):  
L. Bruno Augustin ◽  
Jigar Golecha ◽  
K.G. Sai Shreenaath ◽  
Vishnu Swami ◽  
M. Suresh
Keyword(s):  
Thermal Energy ◽  
Waste Heat ◽  
Electrical Energy ◽  
Operating Conditions ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Solar Thermal Energy ◽  
Thermally Driven ◽  
Absorption Refrigeration System ◽  
Bubble Pump

Increase in the consumption of electrical energy worldwide has laid the emphasis on replacing electrical energy with thermal energy wherever possible. In this paper, the bubble pump, which is ‘heart’ of diffusion- absorption refrigeration system, has been investigated numerically. A thermally driven bubble pump, which can be powered by waste heat or solar thermal energy, is used to lift the liquid. As a result of the absence of any mechanical moving part, the refrigerator is silent and very reliable in addition to aneconomicalandenvironmental friendlydevice. The concept of such a pump is already in existence but optimization studies are yet to be extensively investigated. This paper deals with the optimization of various parameters of the bubble pump usingwateras the working fluid. Parametric studies are carried out and a design optimization for maximum efficiency is performed for various operating conditions.Numerical simulation of the bubble pump is carried out using simple numerical equations which assume slug flow in the bubble pump. The diameter of the pipe and the position of the heating element are varied and the effect it has on time taken, pumping ratio and pumping ratio for one pumping cycle is studied.

Improving the energy efficiency of a 110 MW thermal power plant by low-cost modification of the cooling system

2018 ◽  
Vol 29 (2) ◽  
pp. 245-259 ◽  
Author(s):  
Milica Jović ◽  
Mirjana Laković ◽  
Miloš Banjac
Keyword(s):  
Energy Efficiency ◽  
Power Plant ◽  
Cooling Tower ◽  
Cooling System ◽  
Thermal Power ◽  
Ambient Air ◽  
Electric Power System ◽  
Operating Conditions ◽  
Cooling Towers ◽  
Tower System

The electric power system of the Republic of Serbia relies mostly on lignite-fired thermal power plants, with 70% of the total electricity generation. Most of these plants are over 30 years old, and investment in their modernization is necessary. The energy efficiency of the 110 MW coal-fired power plant in which the condenser is cooled by the mechanical draught wet cooling towers system is analyzed in this paper. Attention is primarily devoted to operating conditions of the cold end of the plant, i.e. to the interrelationship of the condenser and cooling towers. Most important parameters that affect the operation of the cooling towers system are ambient air temperature and relative humidity, specific mass flow rate, and temperature of cooled water. With the existing cooling system, the overall energy efficiency of the plant is low, especially in the summer months, even less than 30%, due to adverse weather conditions. By upgrading existing cooling tower system by adaptation of two additional cooling tower cells, overall energy efficiency can be increased by 1.5%. The cooling tower system rehabilitation investments payback period is estimated to be less than one year. Static method for economic and financial assessment is used.

Thermo-Economic Analysis of a Solar Heating and Cooling System With Desiccant-Based Air Handling Unit by Means of Dynamic Simulations

2014 ◽  
Author(s):  
Giovanni Angrisani ◽  
Carlo Roselli ◽  
Maurizio Sasso ◽  
Francesco Tariello
Keyword(s):  
Environmental Performance ◽  
Cooling System ◽  
Experimental Tests ◽  
Simulation Software ◽  
Solar Heating ◽  
Test Facility ◽  
Solar Thermal Energy ◽  
Dynamic Simulations ◽  
Heating And Cooling ◽  
Air Handling Unit

Solar Heating and Cooling systems are a virtuous alternative to conventional air conditioning plants, as a renewable energy source (solar energy) is exploited. In this paper the coupling of low temperature solar devices with an innovative desiccant-based air handling unit, which meets the sensible and latent loads of a simulated lecture room, is analyzed through TRNSYS dynamic simulation software. The components have been characterized by means of experimental tests carried out at the test facility of Università degli Studi del Sannio. The desiccant-based air handling unit current set-up allows summer operation only. However, heating operation is also simulated, as comfort conditions can be maintained in the conditioned space exploiting solar thermal energy also in winter, with some modifications to the air handling unit. A parametric analysis is performed to compare different technical solutions (collector types, surface, tilt angle) and to identify the optimal one, taking into account energy, economic and environmental performance with respect to a reference system. The best case in terms of energy and environmental performance is represented by evacuated collectors, achieving a primary energy saving of 64% and a CO2 emissions reduction of 61%; flat-plate collectors are instead the best solution in terms of pay-back period (6 years).

scholarly journals Selection of low temperature thermal power cycles

2020 ◽  
pp. 165-165
Author(s):  
Mukundjee Pandey ◽  
Biranchi Padhi ◽  
Ipsita Mishra
Keyword(s):  
Low Temperature ◽  
Thermal Energy ◽  
High Efficiency ◽  
Thermal Power ◽  
Organic Rankine Cycle ◽  
Operating Conditions ◽  
Solar Thermal ◽  
Heat Extraction ◽  
Solar Thermal Energy ◽  
Kalina Cycle

In today?s world, we are facing the problem of fossil fuel depletion along with its cost continuously increasing. Also, it is getting difficult to live in a pollution free environment. Solar energy is one of the most abundantly and freely available form of energy. Out of the various ways to harness solar en-ergy, solar thermal energy is the most efficient as compared to photo-voltaic technology. There are various cycles to convert the solar thermal energy to mechanical work, but Kalina cycle (KC) is one of the best candidates for high efficiency considerations. Therefore, the authors have proposed a novel KC having the double separator arrangements to increase the amount of ammonia vapors at the inlet of turbine, and hence have tried to minimize the pumping power for Double Separator Kalina Cycle (DS-KC) by reducing the fraction of gas/vapors through it. Here, in this paper we have tried to com-pare Organic Rankine Cycle (ORC), Brayton Cycle (BC) and Double Sepa-rator Kalina Cycle (DS-KC) for low temperature heat extraction from para-bolic trough collectors having arc-circular plug with slits (PTC). The effect of different operating conditions; like the number of PTCs, mass flow rate of fluids in different cycles, pressure difference in turbine are analyzed. The ef-fect of these different operating conditions on different parameters like net work done, heat lost by condenser, thermal efficiency and installation cost per unit kW for DS-KC, ORC and BC are studied.

Roofs and Walls of Buildings as a Media for Converting Solar Thermal Energy into Electrical Energy

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Rifky ◽  
Agus Fikri ◽  
Mohammad Mujirudin
Keyword(s):  
Thermal Energy ◽  
Temperature Difference ◽  
Heat Sink ◽  
Thermoelectric Generator ◽  
Cooling System ◽  
Solar Thermal ◽  
Solar Thermal Energy ◽  
Cold Side ◽  
Generator System ◽  
Building Model

Solar energy can be used by buildings. Parts of the building can convert solar thermal energy into electrical energy.The roof and walls are the parts of the building that receive the most sunlight. Therefore, the roof and walls of the building can supply electricity with the thermoelectric generator. The aim of this research is to get the maximum possible output power from the thermoelectric generator system. From the output power produced, it will be possible to find the feasibility of a thermoelectric generator to be used as an energy source for the roof and walls of the building model. The building model is designed simply where the roof and walls can be located a thermoelectric generator system, which consists of a heat sink, a thermoelectric circuit and a cooling system. The heat sink used is aluminum. The thermoelectric circuit consists of 15 sets which are assembled in a series connection arrangement. The cooling system used is active cooling, where water as the cooling fluid circulates continuously during the operation of the system. The thermoelectric hot side temperature is obtained from solar thermal radiation through a heat sink. Meanwhile, the temperature on the cold side of the thermoelectric is the result of the effect of the cooling system that is attached. The temperature difference between the hot and cold sides of the thermoelectric produces a system output in the form of electric voltage and electric current. This study obtain that the generator system on the roof with a temperature difference of 8.90 oC on the hot-cold side produces a power of 1.953 watts. While the generator system on the wall with a temperature difference between the hot-cold side of 1.80 oC produces a power of 0.030 watts.

scholarly journals Experimental Verification of the Performance of the Floor Cooling System in Comparison with the Ceiling Cooling System While Maintaining Thermal Comfort in the Environment

2020 ◽  
Vol 328 ◽  
pp. 02004
Author(s):  
Pavol Mičko ◽  
Andrej Kapjor ◽  
Šimon Kubas ◽  
Martin Vantúch
Keyword(s):  
Thermal Comfort ◽  
Cooling System ◽  
Residential Buildings ◽  
Point Of View ◽  
Hot Water ◽  
Building Structures ◽  
Energy Prices ◽  
Heating And Cooling ◽  
The Right ◽  
Floor System

The trend of constantly increasing energy prices can be observed especially in the increased demands on the thermal insulation properties of building structures. The possibilities of reducing the energy intensity of residential buildings also include the right choice of technology for heating, cooling and hot water preparation. Different cooling systems have different proportions of convection and radiant components. This results in a variety of temperature profiles, and thus also directly affect the quality of the environment in terms of thermal comfort. For efficient heating, it is therefore best to choose a cooling system with a minimum temperature gradient in both the horizontal and vertical directions. At the same time, however, the investment costs for the cooling system must be considered. From this point of view, it seems to be most advantageous to use one system for both heating and cooling. From the point of view of comfort, the most suitable choice of cooling system is ceiling cooling. On the contrary, this system is less suitable for heating compared to the floor system. Therefore, if you are considering the design of a system that will be the greater part of the operation for heating the building and during the summer months will be used to increase thermal comfort by cooling in buildings with lower heat loads [1].

Sign in / Sign up

Export Citation Format

Share Document