scholarly journals Numerical Evaluation of a HVAC System Based on a High-Performance Heat Transfer Fluid

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3298
Author(s):  
Gianpiero Colangelo ◽  
Brenda Raho ◽  
Marco Milanese ◽  
Arturo de Risi
Keyword(s):  
Heat Transfer ◽  
High Performance ◽  
Cooling System ◽  
Electrical Energy ◽  
Simulation Software ◽  
Heat Transfer Fluid ◽  
Hvac System ◽  
Dynamic Simulations ◽  
Heating And Cooling ◽  
The University

Nanofluids have great potential to improve the heat transfer properties of liquids, as demonstrated by recent studies. This paper presents a novel idea of utilizing nanofluid. It analyzes the performance of a HVAC (Heating Ventilation Air Conditioning) system using a high-performance heat transfer fluid (water-glycol nanofluid with nanoparticles of Al2O3), in the university campus of Lecce, Italy. The work describes the dynamic model of the building and its heating and cooling system, realized through the simulation software TRNSYS 17. The use of heat transfer fluid inseminated by nanoparticles in a real HVAC system is an innovative application that is difficult to find in the scientific literature so far. This work focuses on comparing the efficiency of the system working with a traditional water-glycol mixture with the same system that uses Al2O3-nanofluid. The results obtained by means of the dynamic simulations have confirmed what theoretically assumed, indicating the working conditions of the HVAC system that lead to lower operating costs and higher COP and EER, guaranteeing the optimal conditions of thermo-hygrometric comfort inside the building. Finally, the results showed that the use of a nanofluid based on water-glycol mixture and alumina increases the efficiency about 10% and at the same time reduces the electrical energy consumption of the HVAC system.

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 Effect of Modified Flow Schemes of Heat Transfer Fluid on the Performance of a Solar Absorption–Cooling System for an Educational Building in Pakistan

2020 ◽  
Vol 10 (9) ◽  
pp. 3327 ◽  
Author(s):  
Iftikhar Bashir Butt ◽  
Jinwang Tan ◽  
Adeel Waqas ◽  
Majid Ali ◽  
Adeel Javed ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Pattern ◽  
Cooling System ◽  
Electrical Energy ◽  
Primary Energy ◽  
Summer Season ◽  
Hot Water ◽  
Heat Transfer Fluid ◽  
Solar Absorption ◽  
Solar Absorption Cooling

Performance of solar absorption cooling systems (SACS) is the focus of contemporary studies for decreasing the electrical energy consumption of buildings as the conventional cooling system of buildings is the main consumer of electrical energy during the summer season in hot–humid climates. In this study, the performance analysis of SACS by manipulating different flow schemes to the heat transfer fluid between different components of the system was performed. TRNSYS model of SACS in an education building located at the city of Peshawar (34.00 N, 71.54 E), Pakistan to encounter the peak cooling load of 108 kW (during operating hours of the building i.e., 09 a.m. to 05 p.m.) is developed and all possible flow schemes of heat transfer fluid between the system’s components were compared. In Scheme-1 (S-1), a conventional flow pattern is used in which the hot water exiting from the chiller unit flows directly toward the stratified thermal storage unit. In Scheme-2 (S-2), the modified flow pattern of hot water exiting from the chiller unit will divert towards the auxiliary unit, if its temperature exceeds the temperature at the hot side outlet of the tank. Another modified flow pattern is Scheme-3 (S-3) in which the hot water leaving the chiller to keep diverting towards the auxiliary unit unless the outlet temperature from the hotter side of the tank would reach the minimum driving temperature (109 °C) of the chiller’s operation. Simulations in TRNSYS evaluates the SACS’s performance of all the schemes (conventional and modified) for the whole summer season and for each month. In general, S-3 with evacuated tube solar collector results in better primary energy saving with the smallest collector area per kilowatt for achieving 50% primary energy saving for the whole summer season.

Cooling of a Finned Cylinder by a Jet Flow of Air

2002 ◽  
Author(s):  
F. Gori ◽  
F. De Nigris ◽  
E. Pippione ◽  
G. Scavarda
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Jet Flow ◽  
Impinging Jets ◽  
Transfer Coefficients ◽  
Electric System ◽  
Heavy Trucks ◽  
Turbo Compressor ◽  
University Of Rome ◽  
The University

The paper describes a patented proposal to use jets of air in the cooling system of heavy trucks. Preliminary tests have been carried out, in the Heat Transfer Laboratory of the University of Rome “Tor Vergata”, to evaluate the heat transfer characteristics of a jet flow of air, impinging onto an externally finned cylinder. The cylinder is internally heated with an electric system. Thermocouples, located inside the cylinder, allow to measure the wall temperatures, in order to calculate the local and average convective heat transfer coefficients. A preliminary design of the practical apparatus, applied to heavy trucks, has been done in cooperation with Iveco. Nozzles are designed to be put after the fan of heavy trucks to converge air, in the form of jets, onto the tube where the charged air is flowing from the outlet of the turbo-compressor. The efficiency of the jet flow increases the cooling performances but, due to the high temperature at the outlet of the turbo-compressor, it may not be enough. The heat transfer cooling performances are enhanced if the tube to be cooled is externally finned. Some preliminary experiments have been carried out in a real scale bank test of an heavy truck engine at the Engineering Testing Laboratories Department of Iveco. Comparisons are done between the experiments and a simple theoretical model. Some conclusions are drawn about the cooling at different fluid dynamics conditions of the impinging jets.

Multiobjective Design Optimization of Microchannel Cooling System Using High Performance Thermal Vias in LTCC Substrates

2013 ◽  
Vol 10 (1) ◽  
pp. 40-47 ◽  
Author(s):  
Aparna Aravelli ◽  
Singiresu S. Rao ◽  
Hari K. Adluru
Keyword(s):  
Heat Transfer ◽  
Design Optimization ◽  
High Performance ◽  
Cooling System ◽  
Optimization Technique ◽  
Optimization Theory ◽  
Thermal Design ◽  
Design Variables ◽  
Microchannel Cooling ◽  
Multiobjective Design

Increased heat generation in semiconductor devices for demanding applications leads to the investigation of highly efficient cooling solutions. Effective options for thermal management include passing of cooling liquid through the microchannel heat sink and using highly conductive materials. In the author's previous work, experimental and computational analyses were performed on LTCC substrates using embedded silver vias and silver columns forming microchannels. This novel technique of embedding silver vias along with forced convection using a coolant resulted in higher heat transfer rates. The present work investigates the design optimization of this cooling system (microheat exchanger) using systems optimization theory. A new multiobjective optimization problem was formulated for the heat transfer in the LTCC model using the log mean temperature difference (LMTD) method of heat exchangers. The goal is to maximize the total heat transferred and to minimize the coolant pumping power. Structural and thermal design variables are considered to meet the manufacturability and energy requirements. Pressure loss and volume of the silver metal are used as constraints. A hybrid optimization technique using sequential quadratic programming (SQP) and branch and bound method of integer programming has been developed to solve the microheat exchanger problem. The optimal design is presented and sensitivity analysis results are discussed.

On Efficient Passive Cooling of Control Rod Drivers

2013 ◽  
Author(s):  
A. N. Gershuni ◽  
A. P. Nishchik ◽  
V. G. Razumovskiy ◽  
I. L. Pioro
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
High Performance ◽  
Cooling System ◽  
Vertical Channel ◽  
Passive Cooling ◽  
Primary Circuit ◽  
Two Phase ◽  
Primary Coolant ◽  
Control Rod

Experimental research of natural convection and the ways of its suppression in an annular vertical channel to simulate the conditions of cooling the control rod drivers of the reactor protection system (RPS) in its so-called wet design, where the drivers are cooled by primary circuit water supplied due to the system that includes branched pipelines, valves, pump, heat exchanger, etc., is reported. Reliability of the drivers depends upon their temperature ensured by operation of an active multi-element cooling system. Its replacement by an available passive cooling system is possible only under significant suppression of natural convection in control rod channel filled with primary coolant. The methods of suppression of natural convection proposed in the work have demonstrated the possibility both of minimization of axial heat transfer and of almost complete elimination of temperature non-uniformity and oscillation inside the channel under the conditions of free travel of moving element (control rod) in it. The obtained results widen the possibilities of substitution of the active systems of cooling the RPS drivers by reliable passive systems, such as high-performance heat-transfer systems of evaporation-condensation type with heat pipes or two-phase thermosyphons as heat-transferring elements.

Continuous Operating Elastocaloric Heating and Cooling Device: Air Flow Investigation and Experimental Parameter Study

2019 ◽  
Author(s):  
Susanne-Marie Kirsch ◽  
Felix Welsch ◽  
Lukas Ehl ◽  
Nicolas Michaelis ◽  
Paul Motzki ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Air Flow ◽  
Experimental Parameter ◽  
Rotation Frequency ◽  
Coefficient Of Performance ◽  
Large Temperature ◽  
Parameter Study ◽  
Or Efficiency ◽  
Heating And Cooling

Abstract Elastocaloric cooling uses solid-state NiTi-based shape memory alloy (SMA) as a non-volatile cooling medium and enables a novel environment-friendly cooling technology without global warming potential. Due to the high specific latent heats activated by mechanical loading/unloading, large temperature changes can be generated in the material. Accompanied by a small required work input, a high coefficient of performance is achievable. Recently, a fully-functional and illustrative continuous operating elastocaloric fluid cooling system based on SMA is developed and realized, using a novel mechanical concept for individual loading and unloading of multiple SMA wire bundles. The fluid-based heat transfer system is designed for efficient heat exchange between the stationary heat source/sink and the SMA elements, operates without any additional heat transfer medium. Rotation frequency and fluid flow-rate are adjustable during operation, which allows adapting the operation point to power- or efficiency-optimized demands. The versatile placement of the in- and outlets allows different duct lengths and counter-flow or parallel-flow experiments. To investigate the air flow parameters at the in- and outlets, as well as the crossflow between the hot and cold side, a measurement system is developed and integrated. In this contribution, the first measurement results of the output temperatures for inlet air flow variation in combination with different rotation frequencies are presented.

scholarly journals Actualization of prospects of thermal usage of groundwater of mines during liquidation

2019 ◽  
Vol 123 ◽  
pp. 01046 ◽  
Author(s):  
Ivan Sadovenko ◽  
Oleksandr Inkin ◽  
Nataliia Dereviahina ◽  
Yuliia Khryplyvets
Keyword(s):  
Heat Transfer ◽  
Mine Water ◽  
Heat Removal ◽  
Heat Pumps ◽  
Heat Transfer Fluid ◽  
Circulation System ◽  
Heating And Cooling ◽  
Environmentally Safe ◽  
Mathcad Software ◽  
Almost All

The aim of the paper is justification of the economically efficient technological scheme for development of a thermal resource of “Stashkov” mine after its closure, ensuring the maintenance of a favorable energy and ecological-hydrogeological regime in the region. A geotechnological scheme of environmentally safe usage of mine water was justified, involving water pumping up to the surface, heat removal and water reverse pumping into the seams. The suggested circulation system is characterized by an increased energy balance, since it is used to extract almost all the groundwater heat, as well as part of the heat of host rocks. In order to estimate the effectiveness of usage of this technology, calculations of usage of mine water as a source of low-potential energy in heat pumps in comparison with other alternatives (groundwater and surface water streams) using Mathcad software were performed, and it was established that this gives great conversion coefficients of mine water. A geotechnological scheme of usage of mine water was developed, which considers heat transfer, filtration direction, velocity and temperature of groundwater during pumping and removal of heat-transfer fluid from an aquifer for heating and cooling of buildings. The mechanism of heat removal in a flooded rock massif of amine during liquidation was studied with justification of environmentally safe usage of mine water.

Thermodynamic Analysis of Heat and Fluid Flow in a Microchannel With Internal Fins

2009 ◽  
Author(s):  
Ramesh Narayanaswamy ◽  
Tilak T. Chandratilleke ◽  
Andrew J. L. Foong
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Thermodynamic Analysis ◽  
Entropy Generation ◽  
High Performance ◽  
Numerical Study ◽  
Three Dimensional ◽  
Heat Sinks ◽  
Heat Transfer Fluid ◽  
Internal Fins

Efficient cooling techniques are one of the critical design requirements for maintaining reliable operational characteristics of modern, miniaturised high performance electronic components. Microchannel heat sinks form an integral part of most devices used for thermal management in electronic equipment cooling. A microchannel of square cross section, having internal longitudinal fins is considered for analysis. A numerical study is carried out to investigate the fluid flow and heat transfer characteristics. Three-dimensional numerical simulations are performed on the microchannel in the presence of a hydrodynamically developed, thermally developing laminar flow. Further on, a thermodynamic analysis is carried out, for a range of fin heights and thermophysical parameters, in order to obtain the irreversibilities due to heat transfer and fluid flow within the microchannel. An optimum fin height, corresponding to the thermodynamically optimum conditions that minimize the entropy generation rates has been obtained. The effect of the presence of internal fins on the entropy generated due to heat transfer, fluid friction, and the total entropy generation is also provided.

scholarly journals Numerical Investigation of The Air Flow Rate Effect Performance of Earth to Air Heat Exchanger Used for Cooling of Poultry Houses

2021 ◽  
Vol 84 (2) ◽  
pp. 167-184
Author(s):  
Mushtaq I. Hasan ◽  
Dhay Mohammed Muter
Keyword(s):  
Heat Exchanger ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cooling System ◽  
Electrical Energy ◽  
Cooling Load ◽  
Heating And Cooling ◽  
Poultry Houses ◽  
Overall Performance

Usually, poultry houses are located in a remote area where there is no electricity, and where there is electricity, it is expensive, so resorting to these solutions is considered important solutions to save electrical energy and provide free cooling. The main part of generated energy is consumed by cooling and heating systems. One of the well-known approaches to implemented heating and cooling system is earth to air heat exchanger (EAHE) system. This system is effective passive heating and cooling systems which can be used with poultry houses and building. This research studies numerically the effect of mass flow rate on the overall performance of earth to air HE for poultry houses. Four parameters (mass flow rate, required rate, required cooling load and pipe lengths) are selected under environment of Nasiriyah city (a city located in the south of Iraq). The study is conducted using PVC material. The study has been done during summer season. The suggested numerical model has been tested and validated using existing approaches selected from literature review papers. This test shows good agreement with results of selected papers. Moreover, validation and simulation results showed that the required cooling load increased with increasing mass flow rate. Also, with the increasing length of pipe of EAHE, the inflow temperature compared to the space temperature is decreased. However, the overall performance factor of EAHEs decreases by the increase of length of pipe and mass flow rate. Which indicate the possibility of using the earth to air heat exchanger for cooling and heating poultry houses and reduce the use of electrical energy.

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