scholarly journals ANALYSIS AND MODELING OF SOLAR EVAPORATOR-COLLECTOR

2015 ◽  
Vol 16 (2) ◽  
pp. 13-29
Author(s):  
Zakaria Mohd. Amin ◽  
M. N. A. Hawlader ◽  
YE Shaochun
Keyword(s):  
Experimental Data ◽  
Heat Pump ◽  
Operating Temperature ◽  
Radiant Energy ◽  
Solar Irradiation ◽  
Working Fluid ◽  
National University ◽  
Flat Plate Collector ◽  
Harmful Effects ◽  
Comprehensive Study

Solar energy is considered a sustainable resource that poses little to no harmful effects on the environment. The performance of a solar system depends to a great extent on the collector used for the conversion of solar radiant energy to thermal energy. A solar evaporator-collector (SEC) is basically an unglazed flat plate collector where refrigerants, such as R134a is used as the working fluid. As the operating temperature of the SEC is very low, it utilizes both solar irradiation and ambient energy leading to a much higher efficiency than the conventional collectors. This capability of SECs to utilize ambient energy also enables the system to operate at night. This type of collector can be locally made and is relatively much cheaper than the conventional collector.   At the National University of Singapore, the evaporator-collector was integrated to a heat pump and the performance was investigated for several thermal applications: (i) water heating, (ii) drying and (iii) desalination. A 2-dimensional transient mathematical model of this system was developed and validated by experimental data. The present study provides a comprehensive study of performance. KEYWORDS: heat pump; evaporator-collector.

Water Heating and Dehumidification With Heat Pump Utilizing Solar, Ambient and Waste Heat

2009 ◽  
Author(s):  
M. N. A. Hawlader ◽  
Zakaria Mohd. Amin ◽  
Shaochun Ye ◽  
Kyaw Thura Win
Keyword(s):  
Heat Pump ◽  
Waste Heat ◽  
Solar Irradiation ◽  
Water Heating ◽  
Two Phase ◽  
Pump System ◽  
Heat Pump System ◽  
A Value ◽  
National University ◽  
Collector Efficiency

The low temperature operation of a heat pump makes it an excellent match for the use of solar energy. At the National University of Singapore, a solar assisted heat pump system has been designed, fabricated and installed to provide water heating and drying. The system also utilizes the air con waste heat, which would normally be released to atmosphere adding to global warming. Experimental results show that the two-phase unglazed solar evaporator-collector, instead of losing energy to the ambient, gained a significant amount due to low operating temperature of the collector. As a result, the collector efficiency attains a value greater than 1, when conventional collector equations are used. With this evaporator-collector, the system can be operated even in the absence of solar irradiation. The waste heat was collected from an air-con system, which maintained a room at 20–22 °C. In the condenser side, water at 60 °C was produced at a rate of 3 liter/minute and the drying capacity was 2.2kg/hour. Maximum COP of the system was found to be about 5.5.

scholarly journals Geothermal source heat pump performance for a greenhouse heating system: an experimental study

2016 ◽  
Vol 47 (3) ◽  
pp. 164-170 ◽  
Author(s):  
Alexandros Sotirios Anifantis ◽  
Simone Pascuzzi ◽  
Giacomo Scarascia-Mugnozza
Keyword(s):  
Experimental Data ◽  
Heat Pump ◽  
Energy Demand ◽  
Thermal Conditions ◽  
Heating System ◽  
Coefficient Of Performance ◽  
Working Fluid ◽  
Geothermal Heat ◽  
Pump Performance ◽  
Heating Energy Demand

Greenhouses play a significant function in the modern agriculture economy even if require great amount of energy for heating systems. An interesting solution to alleviate the energy costs and environmental problems may be represented by the use of geothermal energy. The aim of this paper, based on measured experimental data, such as the inside greenhouse temperature and the heat pump performance (input and output temperatures of the working fluid, electric consumption), was the evaluation of the suitability of low enthalpy geothermal heat sources for agricultural needs such as greenhouses heating. The study was carried out at the experimental farm of the University of Bari, where a greenhouse was arranged with a heating system connected to a ground-source heat pump (GSHP), which had to cover the thermal energy request. The experimental results of this survey highlight the capability of the geothermal heat source to ensue thermal conditions suitable for cultivation in greenhouses even if the compressor inside the heat pump have operated continuously in a fluctuating state without ever reaching the steady condition. Probably, to increase the performance of the heat pump and then its coefficient of performance within GSHP systems for heating greenhouses, it is important to analyse and maximise the power conductivity of the greenhouse heating system, before to design an expensive borehole ground exchanger. Nevertheless, according to the experimental data obtained, the GSHP systems are effective, efficient and environmental friendly and may be useful to supply the heating energy demand of greenhouses.

scholarly journals SUBSTATIATION OF THE WORKING FLUID TEMPERATURE WHEN TESTING DIESEL INJECTORS

2019 ◽  
Vol 51 (3) ◽  
pp. 99-106
Author(s):  
A.V. Negovora ◽  
◽  
R.G. Magafurov ◽  
A.I. Nizamutdinov ◽  
◽  
...  
Keyword(s):  
Experimental Data ◽  
Diesel Fuel ◽  
Fuel Injection ◽  
Operating Temperature ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Optimum Temperature ◽  
Technical Documentation ◽  
Fuel Temperature

This paper substantiates the permissible temperature limits of the working fluid when testing diesel fuel equipment. The normative and technical documentation does not indicate the optimum temperature of the working fluid during the test. The results are confirmed by experimental data obtained on a device developed by the authors for evaluating the injection characteristics. The developed device was based on the method of fuel injection into a long pipeline. The tests revealed the effect of fuel temperature on the performance of diesel fuel equipment. Also, the tests proved that in order to obtain reliable indicators when diagnosing diesel fuel equipment it is necessary to stably maintain the operating temperature of the device in the range of 60 ± 5 °С.

First and Second Law Analysis of a Flat Plate Collector Working With Nanofluids

2018 ◽  
Author(s):  
M. T. Nitsas ◽  
I. P. Koronaki ◽  
L. Prentza
Keyword(s):  
Flat Plate ◽  
Second Law Of Thermodynamics ◽  
Climatic Conditions ◽  
Working Fluid ◽  
Second Law ◽  
Inlet Temperature ◽  
Water Tank ◽  
Systems Quality ◽  
Typical Day ◽  
Flat Plate Collector

The utilization of solar energy in thermal energy systems was and always be one of the most effective alternative to conventional energy resources. Energy efficiency is widely used as one of the most important parameters in order to evaluate and compare thermal systems including solar collectors. Nevertheless, the first law of thermodynamics is not solely capable of describing the quantitative and qualitative performance of such systems and thus exergy efficiency is used so as to introduce the systems’ quality. In this work, the performance of a flat plate solar collector using water based nanofluids of different nanoparticle types as a working fluid is analyzed theoretically under the climatic conditions in Greece based on the First and Second Law of Thermodynamics. A mathematical model is built and the model equations are solved iteratively in a MATLAB code. The energy and exergy efficiencies as well as the collector losses coefficient for various parameters such as the inlet temperature, the particles concentration and type are determined. Moreover, a dynamic model is built so as to determine the performance of a flat plate collector working with nanofluids and the useful energy that can be stored in a water tank. The exergy destruction and exergy leakage are determined for a typical day in summer during which high temperatures and solar intensity values are common for the Greek climate.

Practical Astronomy Education at the National University of Singapore (NUS)

2019 ◽  
Vol 01 (01) ◽  
pp. 1950004
Author(s):  
A. Yang ◽  
S. C. Cindy Ng ◽  
Q. Leong ◽  
M. H. Tan ◽  
P. Agarwal ◽  
...  
Keyword(s):  
Experimental Data ◽  
General Education ◽  
Scientific Theory ◽  
State Of The Art ◽  
Educational Institutions ◽  
Astronomy Education ◽  
National University ◽  
Robotic Telescope ◽  
Astronomy And Astrophysics

Singapore is not known for astronomy research. However, the interest in astronomy has grown since the 1990s, when more educational institutions and observatories were built to equip students with the skills and knowledge in astronomy. The National University of Singapore (NUS) currently has a strong and rigorous astronomy and astrophysics programme that leads to an astrophysics specialization within the physics B.Sc. degree as well as four general education modules in astronomy and astrophysics. As experimental data is the final arbiter of any scientific theory, we emphasize the practical aspects of astronomy in this programme. We also have a state-of-the-art observatory equipped with a robotic telescope and a planetarium for tutorials. This paper outlines the philosophy, pedagogy and approach of how our NUS team has achieved a very successful undergraduate astronomy and astrophysics for aspiring Singaporean youth.

scholarly journals Experimental Investigation on Evaluation of Thermal Performance of Solar Heating System Using Al2O3 Nanofluid

2020 ◽  
Vol 10 (16) ◽  
pp. 5521 ◽  
Author(s):  
Youngho Lee ◽  
Hyomin Jeong ◽  
Ji-Tae Park ◽  
Antonio Delgado ◽  
Sedong Kim
Keyword(s):  
Power Systems ◽  
Electronic Conductivity ◽  
Heating System ◽  
Solar Irradiation ◽  
Working Fluid ◽  
Solar Systems ◽  
Collector System ◽  
Thermal Changes ◽  
Transfer Properties ◽  
Al2o3 Nanofluid

Over the years, solar collecting systems have gained interest in renewable energy. This study investigated improving the efficiency of the working fluid in thermal solar systems by using nanofluids with three concentrations of alumina, 0.1, 0.3, and 0.5 wt%. The UV-vis absorbance, electronic conductivity, and thermal transfer properties of the nanofluids were analyzed, and the thermal changes with exposure to solar radiation in an experimental collector system were measured by pyranometer. The electronic conductivity, thermal conductivity, and UV-vis absorbance increased with the alumina concentration. Moreover, the temperatures of the nanofluids increased more under solar irradiation than that of distilled water. This implies that the alumina nanofluids absorb solar energy more efficiently than water. The findings of this study suggest that the use of both alumina nanofluids and nanoparticles will improve the efficiency of thermal solar power systems.

Combined Solar Heating and Cooling Systems: Simulation and Design Optimization

2008 ◽  
Author(s):  
Giovanni Nurzia ◽  
Giuseppe Franchini ◽  
Antonio Perdichizzi
Keyword(s):  
Design Optimization ◽  
Heat Pump ◽  
Solar Heating ◽  
Solar Irradiation ◽  
Space Heating ◽  
Thermal Source ◽  
Absorption Chiller ◽  
Cooling Systems ◽  
Detailed Model ◽  
Heating And Cooling

The deployment of solar driven air conditioning is a feasible target in all countries where high solar irradiation matches high cooling loads in buildings: the goal is to gradually replace compression chillers and reduce peak electricity demand during summer. Moreover, as solar thermal collectors are installed, solar cooling systems can be profitably employed during winter. In the present work a code has been implemented for the simulation and the design optimization of combined solar heating and cooling systems. The following system layout has been considered: in warm months the cooling demand is satisfied by means of an absorption chiller — driven by a solar collector field — and a reversible heat pump operating in series. A hot storage matches the variability of solar radiation, while a cold storage smoothes the non-stationarity of cooling demand. During winter, the reversible compression heat pump operates for space heating. Solar collectors are used as thermal source at the evaporator of the heat pump, increasing its coefficient of performance. The code, based on TRNSYS platform, is able to simulate the system throughout a year. Besides TRNSYS standard components a detailed model of the absorption chiller has been included, in order to accurately simulate its off-design operation. Using an optimization tool the size of each component is identified for a given space heating and cooling demand. The minimization of life cycle costs of the system has been chosen as the objective of the optimization. Results of a case study are presented and discussed for a solar heating and cooling plant in an office building. The optimization procedure has been carried out with simulations for a typical Northern Italy town (Alpine climate) and a typical Southern Italy town (Mediterranean climate).

Heat Transport Limitation of a Triangular Micro Heat Pipe

2003 ◽  
Author(s):  
D. Sugumar ◽  
Kek Kiong Tio
Keyword(s):  
Heat Pipe ◽  
Heat Transport ◽  
Operating Temperature ◽  
Working Fluid ◽  
Transport Capacity ◽  
Condenser Section ◽  
Micro Heat Pipe ◽  
Evaporator Section ◽  
Higher Temperature ◽  
Specific Temperature

A micro heat pipe will operate effectively by achieving its maximum possible heat transport capacity only if it is to operate at a specific temperature, i.e., design temperature. In reality, micro heat pipe’s may be required to operate at temperatures different from the design temperature. In this study, the heat transport capacity of an equilateral triangle micro heat pipe is investigated. The micro heat pipe is filled optimally with working fluid for a specific design temperature and operated at different operating temperatures. For this purpose, water, pentane and acetone was selected as the working fluids. From the numerical results obtained, it shows that the optimal charge level of the micro heat pipe is dependent on the operating temperature. Furthermore, the results also shows that if the micro heat pipe is to be operated at temperatures other than its design temperature, its heat transport capacity is limited by the occurrence of flooding at the condenser section or dryout at the evaporator section, depending on the operating temperature and type of working fluid. It is observed that when the micro heat pipe is operated at a higher temperature than its design temperature, the heat transport capacity increases but limited by the onset of dryout at the evaporator section. However, the heat transport capacity decreases if it is to be operated at lower temperatures than its design temperature due to the occurrence of flooding at condenser end. From the results obtained, we can conclude that the performance of a micro heat pipe is decreased if it is to be operated at temperatures other than its design temperature.

An experimental evaluation of R11 as a heat pump working fluid in comparison with some other working fluids

1983 ◽  
Vol 7 (2) ◽  
pp. 129-135
Author(s):  
S. E. Ogbeide ◽  
S. A. K. El-Meniawy ◽  
S. Devotta ◽  
F. A. Watson ◽  
F. A. Holland
Keyword(s):  
Heat Pump ◽  
Experimental Evaluation ◽  
Working Fluid ◽  
Working Fluids
Sign in / Sign up

Export Citation Format

Share Document