References of "Applied Thermal Engineering"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailCharacterization and modeling of a scroll expander with air and ammonia as working fluid
Mendoza, Luis Carlos; Navarro-Esbrí; Bruno, Joan Carles et al

in Applied Thermal Engineering (2014), 70

This paper presents the experimental characterization and modeling of a scroll expander. The expander used here is a scroll compressor modified to work as an expander. It is characterized in two ... [more ▼]

This paper presents the experimental characterization and modeling of a scroll expander. The expander used here is a scroll compressor modified to work as an expander. It is characterized in two experimental setups using air and ammonia as working fluids. The paper studies how the main operating variables (supply pressure and temperature, pressure ratio, rotational speed and lubrication) influence the performance of the scroll expander. A semi-empirical model is proposed to determine the scroll expander performance. This model uses some semi-empirical parameters (such as built-in volume ratio, leakage area and mechanical losses), obtained through experimentation, to calculate the mechanical power, supply mass flow rate and exhaust temperature. Using this semi-empirical model, the deviations in the calculated mechanical power, exhaust temperature and supply mass flow rate are ±9%, ±4 K and ±5% Hz. [less ▲]

Detailed reference viewed: 22 (0 ULg)
Full Text
Peer Reviewed
See detailThermo-hydraulic characterization of an automotive intercooler for a low pressure EGR application
Cuevas, Cristian; Makaire, Danielle ULg; Ngendakumana, Philippe ULg

in Applied Thermal Engineering (2011), 31(14-15), 2474-2484

In this work an experimental study is carried out to determine the thermo-hydraulic performance of an intercooler (IC) with flat tubes provided with triangular plain internal fins and louvered external ... [more ▼]

In this work an experimental study is carried out to determine the thermo-hydraulic performance of an intercooler (IC) with flat tubes provided with triangular plain internal fins and louvered external fins when it is used on a car equipped with a low pressure EGR. The main unknowns to be answered are the thermo-hydraulic characteristics of the IC working under humid conditions induced by EGR, the conditions under which the water content in the mixture of air and exhaust gases begins to condense and the conditions under which the condensed water will be retained inside the IC. The exhaust gases are here replaced by a mixture of dry air and water vapour which are mixed upstream of the IC. The IC is submitted at the following testing conditions: on the ambient air side, the air temperature is fixed at around 20 °C and the air velocity is settled at 1, 2 and 4 ms/s; on the exhaust gases side, the supply temperature was varied between 90 and 150 °C, with dry gas flow rates of 20, 50 and 100 g /s, and water contents varying between almost 0 and 0.09 kgw kgg-1. At these conditions the IC transfers between 1 and 13 kW with overall heat transfer conductance varying between 0.05 and 0.38 kWK-1 and effectivenesses between 0.3 and 0.97. A water accumulation inside the IC was detected for the tests carried out at low dry gas flow rate of 20 g s-1 and for all the water content explored here (higher than 0.02 kgw kgg-1). [less ▲]

Detailed reference viewed: 53 (7 ULg)
Full Text
Peer Reviewed
See detailAir-side particulate fouling of microchannel heat exchangers: Experimental comparison of air-side pressure drop and heat transfer with plate-fin heat exchanger
Bell, Ian ULg; Groll, Eckhard

in Applied Thermal Engineering (2011), 31(5), 742-749

In this study, the air-side pressure drop and heat transfer performance of plate-fin and microchannel coils were tested under clean and fouled conditions. The heat exchangers were tested with two ... [more ▼]

In this study, the air-side pressure drop and heat transfer performance of plate-fin and microchannel coils were tested under clean and fouled conditions. The heat exchangers were tested with two different types of dust, ASHRAE dust and Arizona Road Test Dust. The ASHRAE dust was found to have a very significant impact on the pressure drop of the microchannel heat exchanger, increasing the air-side pressure drop of the microchannel heat exchanger over 200% for a dust injection of 267g (1612.5 g/m2). Fouling of the microchannel heat exchanger with Arizona Road Test Dust was not found to increase the air-side pressure drop of the microchannel heat exchanger but was found to decrease the heat transfer rate by more than 10%. In addition, from studies of the evolution of the air-side pressure drop during the fouling process, it is seen that microchannel coils with louvered fins with fin pitch below 2.0 mm were significantly more prone to fouling than louvered heat exchangers with larger fin pitch. Particulate fouling of the wavy-plate-fin heat exchanger resulted in significantly lower reductions in heat transfer and increase in air-side pressure drop than for the microchannel heat exchanger. [less ▲]

Detailed reference viewed: 26 (3 ULg)
Full Text
Peer Reviewed
See detailThermo-Economic optimization of waste heat recovery Organic Rankine Cycles
Quoilin, Sylvain ULg; Declaye, Sébastien ULg; Tchanche, Bertrand F. et al

in Applied Thermal Engineering (2011)

The present paper focuses both on the thermodynamic and on the economic optimization of a small scale ORC in waste heat recovery application. A sizing model of the ORC is proposed, capable of predicting ... [more ▼]

The present paper focuses both on the thermodynamic and on the economic optimization of a small scale ORC in waste heat recovery application. A sizing model of the ORC is proposed, capable of predicting the cycle performance with different working fluids and different components sizes. The working fluids considered are R245fa, R123, n-butane, n-pentane and R1234yf and Solkatherm. Results indicate that, for the same fluid, the objective functions (economics profitability, thermodynamic efficiency) lead to different optimal working conditions in terms of evaporating temperature: the operating point for maximum power doesn’t correspond to that of the minimum specific investment cost: The economical optimum is obtained for n-butane with a specific cost of 2136 €/kW, a net output power of 4.2 kW, and an overall efficiency of 4.47%, while the thermodynamic optimum is obtained for the same fluid with an overall efficiency of 5.22%. It is also noted that the two optimizations can even lead to the selection of a different working fluid. This is mainly due to additional fluid properties that are not taken into account in the thermodynamic optimization, such as the fluid density: a lower density leads to the selection of bigger components which increases the cost and decreases the economical profitability. [less ▲]

Detailed reference viewed: 371 (45 ULg)
Full Text
Peer Reviewed
See detailRadiant ceiling systems coupled to its environment part 2: Dynamic modeling and validation
Fonseca, Nestor; Bertagnolio, Stéphane ULg; Cuevas, Cristian

in Applied Thermal Engineering (2010), 30

This paper presents the results of a study performed in order to develop a dynamic model of radiant ceiling panels in heating or cooling modes coupled to its environment (fenestration, walls, internal ... [more ▼]

This paper presents the results of a study performed in order to develop a dynamic model of radiant ceiling panels in heating or cooling modes coupled to its environment (fenestration, walls, internal loads and ventilation system). The model considers the radiant panels as a dynamic-state finned heat exchanger connected to a detailed lumped dynamic model of the building (ReC network). The behavior of the radiant ceiling system and the interactions with its environment has been experimentally and numerically evaluated. Using as inputs the radiant ceiling and room dimensions, material properties and the transient measurements of air temperature at the adjacent zones, supply air and water temperatures and mass flow rates, the model allows for the estimation of the water exhaust temperature, radiant ceiling average surface temperature, resultant and dry air room temperatures, radiant ceiling power and internal surface temperatures of the room in order to compare with measurements taken during the commissioning process. Two dynamic tests in heating and cooling modes are used to validate the model. [less ▲]

Detailed reference viewed: 61 (14 ULg)
Full Text
Peer Reviewed
See detailCharacterization of a scroll compressor under extended operating conditions
Cuevas, Cristian; Lebrun, Jean ULg; Lemort, Vincent ULg et al

in Applied Thermal Engineering (2010), 30

Refrigeration and air-conditioning compressors are designed to work under well-defined conditions. In some applications it is interesting to observe their performances beyond these conditions, for example ... [more ▼]

Refrigeration and air-conditioning compressors are designed to work under well-defined conditions. In some applications it is interesting to observe their performances beyond these conditions, for example in the case of a high temperature two-stage heat pump or of a cooling system working at high temperature. In this study a compressor is characterized experimentally with refrigerant R134a and through 118 tests at condensing pressures varying from 8.6 up to 40.4 bar (tsat = 33.9°C to tsat = 100.8°C) and evaporating pressures varying from 1.6 up to 17.8 bar (tsat = -15.6°C to tsat = 62.4°C). Under these conditions the compressor motor was pushed at its maximal current in several tests. This compressor’s performance is mainly characterized by its isentropic and volumetric efficiencies. It presents a maximal isentropic efficiency of 72%, corresponding to a pressure ratio of around 2.5–2.6. The volumetric efficiency decreases linearly from almost 1.0 (for a pressure ratio of 1.3) to 0.83 (for a pressure ratio of 9.7). A slight degradation of the isentropic and volumetric efficiencies is observed when the compressor supply and exhaust pressures are increased for a given pressure ratio; this could be due to an internal leakage. The compressor tests are used to identify the six parameters of a semi-empirical simulation model. After parameter identification, experimental and simulated results are in very good agreement, except for some points at high compressor power where the compressor is pushed at its maximal current. [less ▲]

Detailed reference viewed: 108 (9 ULg)
Full Text
Peer Reviewed
See detailRadiant ceiling systems coupled to its environment part 1: Experimental analysis
Fonseca, Néstor; Cuevas, Cristian; Lemort, Vincent ULg

in Applied Thermal Engineering (2010), 30

This paper presents the results of an experimental analysis of the radiant ceiling systems in both heating and cooling modes coupled to its environment (fenestration, walls, internal loads and ventilation ... [more ▼]

This paper presents the results of an experimental analysis of the radiant ceiling systems in both heating and cooling modes coupled to its environment (fenestration, walls, internal loads and ventilation system). The main objective of this study is to present the results of the experimental analysis and measurement methods and its discussion. Two test chambers are adapted in a way to reproduce as good as possible the characteristics of the real offices located in Brussels (Belgium). Forty-six tests are performed to observe the influence of parameters such as the mass flow rate, supply water temperature, fenestration and ventilation system effects and thermal load distribution. Laboratory test results show that the influence of surfaces temperatures inside the room, especially the facade, is considerable. Therefore, the system must be evaluated together with its designed environment and not as separate HVAC equipment. [less ▲]

Detailed reference viewed: 34 (2 ULg)
Full Text
Peer Reviewed
See detailDevelopment and validation of a condenser three zones model
Cuevas, Cristian; Lebrun, Jean ULg; Lemort, Vincent ULg et al

in Applied Thermal Engineering (2009)

A general and simple ‘‘deterministic” model of a refrigeration condenser is presented. The model assumes that the condenser can be divided into three distinct zones on the refrigerant side: the vapour de ... [more ▼]

A general and simple ‘‘deterministic” model of a refrigeration condenser is presented. The model assumes that the condenser can be divided into three distinct zones on the refrigerant side: the vapour de-superheating zone, the two-phase zone and the sub-cooled liquid zone. The model inputs are the air supply temperature, the air mass flow rate, the refrigerant supply temperature (or the over-heating), the exhaust sub-cooling and the refrigerant mass flow rate. The model is able to identify the pressures and temperatures in each zone and the corresponding heat flows. The model also gives the geometrical repartition among the zones and the pressure drop on air-side. The condenser model is validated with a total of 183 tests. Testing conditions cover a very wide domain, including pressures up to 40 bars with refrigerant R134a. The model is able to predict with a probability of 95% the condenser supply pressure within a confidence interval of +0.5 and 0.1 bar. This means a condenser power confidence interval within 200 and +100 W, which is considered here as acceptable. Refrigerant pressure drop is predicted with a higher error, but it is attributed to measuring uncertainty. On the other hand, air pressure drop is predicted with a very poor accuracy. Undoubtedly, this is due to the friction factor correlation used in this study which is not the most adequate. Here a difference of 40% is obtained. [less ▲]

Detailed reference viewed: 134 (18 ULg)
Full Text
Peer Reviewed
See detailTesting and modeling a scroll expander integrated into an Organic Rankine Cycle
Lemort, Vincent ULg; Quoilin, Sylvain ULg; Cuevas, Cristian et al

in Applied Thermal Engineering (2009), 29

Organic Rankine Cycles (ORC’s) are particularly suitable for recovering energy from low-grade heat sources. This paper first presents the results of an experimental study carried out on a prototype of an ... [more ▼]

Organic Rankine Cycles (ORC’s) are particularly suitable for recovering energy from low-grade heat sources. This paper first presents the results of an experimental study carried out on a prototype of an open-drive oil-free scroll expander integrated into an ORC working with refrigerant HCFC-123. By exploiting the overall expander performance measurements, the eight parameters of a scroll expander semi-empirical model are then identified. The model is able to compute variables of first importance such as the mass flow rate, the delivered shaft power and the discharge temperature, and secondary variables such as the supply heating-up, the exhaust cooling-down, the ambient losses, the internal leakage and the mechanical losses. The maximum deviation between the predictions by the model and the measurements is 2% for the mass flow rate, 5% for the shaft power and 3 K for the discharge temperature. The validated model of the expander is finally used to quantify the different losses and to indicate how the design of the expander might be altered to achieve better performances. This analysis pointed out that the internal leakages and, to a lesser extent, the supply pressure drop and the mechanical losses are the main losses affecting the performance of the expander. [less ▲]

Detailed reference viewed: 370 (37 ULg)
Full Text
Peer Reviewed
See detailMathematical description of heat and mass transfer during deep-bed drying: effect of product shrinkage on bed porosity
Bennamoun, Lyes ULg; belhamri, Azeddine

in Applied Thermal Engineering (2008), 18(17-18), 2236-2244

Detailed reference viewed: 17 (3 ULg)
Full Text
Peer Reviewed
See detailA comparison of advanced thermal cycles suitable for upgrading existing power plant
Heyen, Georges ULg; Kalitventzeff, Boris ULg

in Applied Thermal Engineering (1999), 19(3), 227-237

In view of the constant growth of electricity usage and public pressure to reduce the dependence on nuclear power plants in the energy supply, solutions are sought to increase the capacity of power plants ... [more ▼]

In view of the constant growth of electricity usage and public pressure to reduce the dependence on nuclear power plants in the energy supply, solutions are sought to increase the capacity of power plants using fossil fuels. Highly efficient cycles are available : gas turbines combined with waste heat boilers and steam cycles are able to achieve efficiencies above 50-55%. However building new plants requires a large amount of capital. Alternative proposals are based on upgrades of existing plants : capital savings are expected by reusing part of the facilities. In the present study, three parallel proposals are compared on the basis of exergy efficiency; cost of investment and flexibility of operation are also discussed. They are compared with classical Rankine cycle and state of the art combined cycles. (C) 1998 Elsevier Science Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 26 (5 ULg)
Full Text
Peer Reviewed
See detailA comparison of advanced thermal cycles suitable for upgrading existing power plants
Heyen, Georges ULg; Kalitventzeff, Boris ULg

in Applied Thermal Engineering (1998), 19

Detailed reference viewed: 7 (3 ULg)
Peer Reviewed
See detailMethodology for optimization of operation to reduce site-scale energy use in production plants
Heyen, Georges ULg; Kalitventzeff, Boris ULg

in Applied Thermal Engineering (1997), 17(8-10), 1005-1014

A methodology was developed to improve energy usage in the process industries by optimizing plant operation. The first step was to build fine tuned site-scale models of energy intensive production plants ... [more ▼]

A methodology was developed to improve energy usage in the process industries by optimizing plant operation. The first step was to build fine tuned site-scale models of energy intensive production plants and of combined heat and power utility distribution networks (heat, power, cooling), and later to optimize them using various numerical techniques. The methodology not only comprises these models, but also the selected optimization methods, their implementation in algorithms suited for the problems to be solved and the evaluation of the results in terms of their applicability ia real industrial problems. The detailed models were tuned on the basis of actual plant data. They were used to calculate accurate energy balances, and thus to identify sources of energy waste. Finally they allowed optimization of energy usage by adjusting operating conditions at a medium time scale (a few hours to a couple of days). Energy savings in the range 5%-10% could be obtained for energy intensive processes, where even a low percentage represents a considerable amount. (C) European Communities 1997. Published by Elsevier Science Ltd. [less ▲]

Detailed reference viewed: 20 (2 ULg)