scholarly journals Thermal evaluation of an indirect air heating system using solar collectors

2021 ◽  
pp. 6-22
Author(s):  
Jeisell Marisol Cabrera-Chairez ◽  
Néstor Manuel Ortíz-Rodríguez ◽  
Rodrigo Cervando Villegas-Martínez ◽  
Juan Manuel García-González
Keyword(s):  
Fossil Fuels ◽  
Heating System ◽  
Hot Water ◽  
Water Tank ◽  
Solar Collectors ◽  
Water Storage Tank ◽  
Air Heating ◽  
Conventional Drying ◽  
Alternative Energies

One of the current problems is the use of energy obtained from fossil fuels, especially due to the emission of greenhouse gases. An option to replace fossil fuels is the use of alternative energies such as solar or wind energy. The objective of this work is to carry out a thermal and energy analysis of an indirect air heating system that receives energy through solar collectors that operate with water as the thermal fluid used in a food dehydration system, in order to know the efficiency of the system and therefore, make improvements to the circuit, in addition to the characterization of the water storage tank of the system, obtain the amount of energy that can be provided and the behavior of temperatures at different operating flows. According to the methodology, the temperature profile was obtained inside the hot water tank in two modes of operation (heating and energy extraction) reaching temperatures of 50 to 70 ° C, where the optimum temperature for drying is found and in turn reaching an efficiency 84%, compared to a conventional drying system that uses LP gas.

An Investigation of a Residential Solar System Coupled to a Radiant Panel Ceiling

1988 ◽  
Vol 110 (3) ◽  
pp. 172-179 ◽  
Author(s):  
Z. Zhang ◽  
M. Pate ◽  
R. Nelson
Keyword(s):  
Heat Exchanger ◽  
Solar System ◽  
Flat Plate ◽  
Storage Tank ◽  
Heating System ◽  
Hot Water ◽  
Radiant Heating ◽  
Solar Collectors ◽  
Water Storage Tank ◽  
Radiant Panel

An experimental study of a solar-radiant heating system was performed at Iowa State University’s Energy Research House (ERH). The ERH was constructed with copper tubes embedded in the plaster ceilings, thus providing a unqiue radiant heating system. In addition, 24 water-glycol, flat-plate solar collectors were mounted on the south side of the residence. The present study uses the solar collectors to heat a storage tank via a submerged copper tube coil. Hot water from the storage tank is then circulated through a heat exchanger, which heats the water flowing through the radiant ceiling. This paper contains a description of the solar-radiant system and an interpretation of the data that were measured during a series of transient experiments. In addition, the performance of the flat-plate solar collectors and the water storage tank were evaluated. The characteristics of a solar-to-radiant heat exchanger were also investigated. The thermal behavior of the radiant ceiling and the room enclosures were observed, and the heat transfer from the ceiling by radiation and convection was estimated. The overall heating system was also evaluated using the thermal performances of the individual components. The results of this study verify that it is feasible to use a solar system coupled to a low-temperature radiant-panel heating system for space heating. A sample performance evaluation is also presented.

Thermal Performance of a Large Low Flow Solar Heating System With a Highly Thermally Stratified Tank

2005 ◽  
Vol 127 (1) ◽  
pp. 15-20 ◽  
Author(s):  
Simon Furbo ◽  
Niels Kristian Vejen ◽  
Louise Jivan Shah
Keyword(s):  
Thermal Performance ◽  
Heat Exchangers ◽  
Heating System ◽  
External Heat ◽  
Solar Heating ◽  
Hot Water ◽  
Low Flow ◽  
Water Tank ◽  
Solar Collectors ◽  
Domestic Water

In year 2000 a 336 m2 solar domestic hot water system was built in Sundparken, Elsinore, Denmark. The solar heating system is a low flow system with a 10000 l hot-water tank. Due to the orientation of the buildings half of the solar collectors are facing east, half of the solar collectors are facing west. The collector tilt is 15° from horizontal for all collectors. Both the east-facing and the west-facing collectors have their own solar collector loop, circulation pump, external heat exchanger and control system. The external heat exchangers are used to transfer the heat from the solar collector fluid to the domestic water. The domestic water is pumped from the bottom of the hot-water tank to the heat exchanger and back to the hot-water tank through stratification inlet pipes. The return flow from the DHW circulation pipe also enters the tank through stratification inlet pipes. The tank design ensures an excellent thermal stratification in the tank. The solar heating system was installed in May 2000. The thermal performance of the solar heating system has been measured in the first two years of operation. Compared to other large Danish solar domestic hot water systems the system is performing well in spite of the fact that the solar collectors are far from being orientated optimally. The utilization of the solar radiation on the collectors is higher, 46% in the second year of operation, than for any other system earlier investigated in Denmark, 16%–34%. The reason for the good thermal performance and for the excellent utilization of the solar radiation is the high hot-water consumption and the good system design making use of external heat exchangers and stratification inlet pipes.

Evacuated Tube Heat Pipe Solar Collectors Applied to Recirculation Loop in a Federal Building: SSA Philadelphia

Solar Energy ◽  
2004 ◽  
Author(s):  
Andy Walker ◽  
Fariborz Mahjouri ◽  
Robert Stiteler
Keyword(s):  
Solar Energy ◽  
Heat Pipe ◽  
Heat Loss ◽  
Heating System ◽  
Hot Water ◽  
Solar Array ◽  
Solar Collectors ◽  
Water Heating ◽  
Evacuated Tube ◽  
Recirculation Loop

This paper describes design, simulation, construction and measured initial performance of a solar water heating system (360 Evacuated Heat-Pipe Collector tubes, 54 m2 gross area, 36 m2 net absorber area) installed at the top of the hot water recirculation loop in the Social Security Mid-Atlantic Center in Philadelphia. Water returning to the hot water storage tank is heated by the solar array when solar energy is available. This new approach, as opposed to the more conventional approach of preheating incoming water, is made possible by the thermal diode effect of heat pipes and low heat loss from evacuated tube solar collectors. The simplicity of this approach and its low installation costs makes the deployment of solar energy in existing commercial buildings more attractive, especially where the roof is far removed from the water heating system, which is often in the basement. Initial observed performance of the system is reported. Hourly simulation estimates annual energy delivery of 111 GJ/year of solar heat and that the annual efficiency (based on the 54 m2 gross area) of the solar collectors is 41%, and that of the entire system including parasitic pump power, heat loss due to freeze protection, and heat loss from connecting piping is 34%. Annual average collector efficiency based on a net aperture area of 36 m2 is 61.5% according to the hourly simulation.

scholarly journals Influence of the Thermometer Inertia on the Quality of Temperature Control in a Hot Liquid Tank Heated with Electric Energy

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 4039
Author(s):  
Dawid Taler ◽  
Tomasz Sobota ◽  
Magdalena Jaremkiewicz ◽  
Jan Taler
Keyword(s):  
Water Temperature ◽  
Time Constant ◽  
Temperature Control ◽  
Complex Structure ◽  
Small Diameter ◽  
Hot Water ◽  
Temperature Control System ◽  
Water Tank ◽  
Water Storage Tank

This paper presents the medium temperature monitoring system based on digital proportional–integral–derivative (PID) control. For industrial thermometers with a complex structure used for measuring the temperature of the fluid under high pressure, the accuracy of the first-order model is inadequate. A second-order differential equation was applied to describe a dynamic response of a temperature sensor placed in a heavy thermowell (industrial thermometer). The quality of the water temperature control system in the tank was assessed when measuring the water temperature with a jacketed thermocouple and a thermometer in an industrial casing. A thermometer of a new design with a small time constant was also used to measure temperature. The quality of water temperature control in the hot water storage tank was evaluated using a classic industrial thermometer and a new design thermometer. In both cases, there was a K-type sheathed thermocouple inside the thermowell. Reductions in the time constant of the new thermometer are achieved by means of a steel casing with a small diameter hole inside which the thermocouple is precisely fitted. The time constants of the thermometers were determined experimentally with a jump in water temperature. A digital controller was designed to maintain the preset temperature in an electrically heated hot water tank. The function of the regulator was to adjust the power of the electrical heater to maintain a constant temperature of the liquid in the tank.

Research at the Building Research Establishment into the applications of solar collectors for space and water heating in buildings

1980 ◽  
Vol 295 (1414) ◽  
pp. 403-414
Keyword(s):  
Solar Collector ◽  
Water System ◽  
Cost Effective ◽  
Heating System ◽  
Field Studies ◽  
Hot Water ◽  
Solar Collectors ◽  
Water Heating ◽  
Actual Performance ◽  
Low Efficiency

A completed study of a solar hot water heating system installed in a school showed an annual average efficiency of 15%, the low efficiency largely caused by the unfavourable pattern of use in schools. Field studies, in 80 existing and 12 new houses, of a simple domestic hot water system have been initiated to ascertain the influence of the occupants on the actual performance of solar collector systems. The development of testing methods of solar collectors and solar water heating systems is being undertaken in close collaboration with the B.S.I. and the E.E.C. Solar space heating is being investigated in two experimental low energy house laboratories, one using conventional solar collectors with interseasonal heat storage and the other a heat pump with an air solar collector. Studies of the cost-effectiveness of solar collector applications to buildings in the U.K. show that they are far less cost-effective than other means of conserving energy in buildings.

scholarly journals Installation and Operation of a Solar Cooling and Heating System Incorporated with Air-Source Heat Pumps

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 996 ◽  
Author(s):  
Li Huang ◽  
Rongyue Zheng ◽  
Udo Piontek
Keyword(s):  
Heating System ◽  
Cooling Capacity ◽  
Heat Pumps ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Energy Yield ◽  
Absorption Chiller ◽  
Annual Average ◽  
Water Storage Tank ◽  
Solar Cooling

A solar cooling and heating system incorporated with two air-source heat pumps was installed in Ningbo City, China and has been operating since 2018. It is composed of 40 evacuated tube modules with a total aperture area of 120 m2, a single-stage and LiBr–water-based absorption chiller with a cooling capacity of 35 kW, a cooling tower, a hot water storage tank, a buffer tank, and two air-source heat pumps, each with a rated cooling capacity of 23.8 kW and heating capacity of 33 kW as the auxiliary system. This paper presents the operational results and performance evaluation of the system during the summer cooling and winter heatingperiod, as well as on a typical summer day in 2018. It was found that the collector field yield and cooling energy yield increased by more than 40% when the solar cooling and heating system is incorporated with heat pumps. The annual average collector efficiency was 44% for cooling and 42% for heating, and the average coefficient of performance (COP) of the absorption chiller ranged between 0.68 and 0.76. The annual average solar fraction reached 56.6% for cooling and 62.5% for heating respectively. The yearly electricity savings accounted for 41.1% of the total electricity consumption for building cooling and heating.

Joint Application of Solar Water Heating System and Air-Conditioning System in a Dormitory Building

2010 ◽  
Vol 171-172 ◽  
pp. 215-218
Author(s):  
Hai Ying Wang ◽  
Song Tao Hu ◽  
Jia Ping Liu
Keyword(s):  
Air Conditioning ◽  
Heating System ◽  
Hot Water ◽  
Water Tank ◽  
Auxiliary Heating ◽  
Water Heating ◽  
Air Conditioning System ◽  
Solar Water Heating ◽  
Solar Water ◽  
Solar Water Heating System

Solar water heating system is used to supply hot water all-year-round for a new dormitory building. Flat solar energy collectors are mounted on the roof. The hot water tank and pumps are installed together with the air conditioning equipments in the plant room. Air cooled heat pump is used to provide cooling in summer, and high temperature water from boiler room (in old building) is used as heat source in winter. Usually auxiliary heating is necessary to improve the stability and reliability of solar water heating system. In this case, we take full use of the equipment of air conditioning system instead of electricity as auxiliary heating resources. In this paper, we introduced the design of the solar water heating system and the auxiliary heating method by air conditioning systems. The control strategies to fulfill all the functions and switch between different conditions are also introduced.

scholarly journals Modelling and testing a passive night-sky radiation system

2017 ◽  
Vol 28 (1) ◽  
pp. 76 ◽  
Author(s):  
G.D. Joubert ◽  
R.T. Dobson
Keyword(s):  
Storage Tank ◽  
Cold Water ◽  
Water Storage ◽  
Heating System ◽  
Hot Water ◽  
Theoretical Simulation ◽  
Water Storage Tank ◽  
Heating And Cooling ◽  
Night Sky ◽  
Radiation Cooling

The as-built and tested passive night-sky radiation cooling/heating system considered in this investigation consists of a radiation panel, a cold water storage tank, a hot water storage tank, a room and the interconnecting pipework. The stored cold water can be used to cool a room during the day, particularly in summer. A theoretical time-dependent thermal performance model was also developed and compared with the experimental results and it is shown that the theoretical simulation model captures the experimental system performance to within a reasonable degree of accuracy. A natural circulation experimental set-up was constructed and subsequently used to show that under local (Stellenbosch, South Africa) conditions the typical heat-removal rate from the water in the tank is 55 W/m2 of radiating panel during the night; during the day the water in the hot water-storage tank was heated from 24 °C to 62 °C at a rate of 96 W/m2. The system was also able to cool the room at a rate of 120 W/m3. The results thus confirmed that it is entirely plausible to design an entirely passive system, that is, without the use of any moving mechanical equipment such as pumps and active controls, for both room-cooling and water-heating. It is thus concluded that a passive night-sky radiation cooling/heating system is a viable energy-saving option and that the theoretical simulation, as presented, can be used with confidence as an energy-saving system design and evaluation tool. Keywords: passive cooling and heating, buoyancy-driven fluid flow, theoretical simulation, experimental verification Highlights:Passively driven renewable energy heating and cooling systems are considered.Time-dependent mathematical simulation model is presented.Experimental buoyancy-driven heating and cooling system built and tested.Experimental results demonstrate the applicability of the theoretical simulation model.Saving and evaluation design tool.

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