The Experts below are selected from a list of 20019 Experts worldwide ranked by ideXlab platform

Pablo Dolado - One of the best experts on this subject based on the ideXlab platform.

  • characterization of melting and solidification in a real scale pcm Air Heat Exchanger experimental results and empirical model
    Renewable Energy, 2011
    Co-Authors: Pablo Dolado, Ana Lazaro, Jose M Marin, Belen Zalba
    Abstract:

    Abstract This paper describes the experimental studies carried out to test thermal cycling of a real-scale PCM–Air Heat Exchanger at ambient temperatures. To achieve this goal an experimental setup previously designed and used for testing real-scale prototypes of PCM–Air Heat Exchangers is modified. The PCM used is commercially available, organic, and paraffin based. The total energy exchanged during melting and solidification, as well as the time elapsed until total melting/solidification are determined from the power curves experimentally obtained. The influence of the inlet Air temperature and Air flow is studied, and results show that the continuous thermal cycling of the unit is a repetitive process: running experiments with similar conditions leads to the same thermal behavior, no degradation in the PCM properties is noticed. Pressure drop is measured for different Air flows. Depending on the inlet Air temperature, full solidification of the PCM could be achieved in less than 3 h for an 8 °C temperature difference between the inlet Air and the average phase change of the PCM. Average thermal powers of up to 4.5 kW and 3.5 kW for 1 h are obtained for melting and solidification stages, respectively. An empirical model is developed from the experimental results, which could be a useful designing tool for applications that use such technology: green housing, curing and drying processes, plant production, HVAC, and free-cooling.

  • characterization of melting and solidification in a real scale pcm Air Heat Exchanger numerical model and experimental validation
    Energy Conversion and Management, 2011
    Co-Authors: Pablo Dolado, Ana Lazaro, Jose M Marin, Belen Zalba
    Abstract:

    Abstract This paper describes the models developed to simulate the performance of a thermal energy storage (TES) unit in a real scale PCM-Air Heat Exchanger, analyzing the Heat transfer between the Air and a commercially available and slab macroencapsulated phase change material (PCM). The models are based on one-dimensional conduction analysis, utilizing finite differences method, and implicit formulation, using the thermo-physical data of the PCM measured in the laboratory: enthalpy and thermal conductivity as functions of temperature. The models can take into account the hysteresis of the enthalpy curve and the convection inside the PCM, using effective conductivity when necessary. Two main paths are followed to accomplish the modeling: the thermal analysis of a single plate, and the thermal behavior of the entire TES unit. Comparisons between measurements and simulations are undertaken to evaluate the models. Average errors of less than 12% on thermal power are obtained for the entire cycle. Once the model is validated, a series of parameters and variables is studied to verify their influence on the behavior and design of the TES unit.

  • characterization of melting and solidification in a real scale pcm Air Heat Exchanger numerical model and experimental validation
    Energy Conversion and Management, 2011
    Co-Authors: Pablo Dolado, Ana Lazaro, Jose M Mari, Ele Zalba
    Abstract:

    Abstract This paper describes the models developed to simulate the performance of a thermal energy storage (TES) unit in a real scale PCM-Air Heat Exchanger, analyzing the Heat transfer between the Air and a commercially available and slab macroencapsulated phase change material (PCM). The models are based on one-dimensional conduction analysis, utilizing finite differences method, and implicit formulation, using the thermo-physical data of the PCM measured in the laboratory: enthalpy and thermal conductivity as functions of temperature. The models can take into account the hysteresis of the enthalpy curve and the convection inside the PCM, using effective conductivity when necessary. Two main paths are followed to accomplish the modeling: the thermal analysis of a single plate, and the thermal behavior of the entire TES unit. Comparisons between measurements and simulations are undertaken to evaluate the models. Average errors of less than 12% on thermal power are obtained for the entire cycle. Once the model is validated, a series of parameters and variables is studied to verify their influence on the behavior and design of the TES unit.

  • pcm Air Heat Exchangers for free cooling applications in buildings empirical model and application to design
    Energy Conversion and Management, 2009
    Co-Authors: Ana Lazaro, Pablo Dolado, Jose M Mari, Ele Zalba
    Abstract:

    This paper presents novel design conclusions based on the experimental results and on an empirical model for a real-scale prototype of a PCM-Air Heat Exchanger. From experimental results, an empirical model was built aimed at simulating the thermal behavior in the tested Heat Exchanger in different cases. These simulations were used to evaluate the technical viability of its application. Since the thermal properties of PCM vary with temperature, a PCM-Heat Exchanger works as a transitory system and therefore, its design must be based on transitory analysis. This work shows that PCM selection criteria must include the power demand. The conclusions obtained for the PCM-Air Heat exchange can be useful for selecting PCM for other Heat Exchanger applications that use the tested geometry.

Belen Zalba - One of the best experts on this subject based on the ideXlab platform.

  • characterization of melting and solidification in a real scale pcm Air Heat Exchanger experimental results and empirical model
    Renewable Energy, 2011
    Co-Authors: Pablo Dolado, Ana Lazaro, Jose M Marin, Belen Zalba
    Abstract:

    Abstract This paper describes the experimental studies carried out to test thermal cycling of a real-scale PCM–Air Heat Exchanger at ambient temperatures. To achieve this goal an experimental setup previously designed and used for testing real-scale prototypes of PCM–Air Heat Exchangers is modified. The PCM used is commercially available, organic, and paraffin based. The total energy exchanged during melting and solidification, as well as the time elapsed until total melting/solidification are determined from the power curves experimentally obtained. The influence of the inlet Air temperature and Air flow is studied, and results show that the continuous thermal cycling of the unit is a repetitive process: running experiments with similar conditions leads to the same thermal behavior, no degradation in the PCM properties is noticed. Pressure drop is measured for different Air flows. Depending on the inlet Air temperature, full solidification of the PCM could be achieved in less than 3 h for an 8 °C temperature difference between the inlet Air and the average phase change of the PCM. Average thermal powers of up to 4.5 kW and 3.5 kW for 1 h are obtained for melting and solidification stages, respectively. An empirical model is developed from the experimental results, which could be a useful designing tool for applications that use such technology: green housing, curing and drying processes, plant production, HVAC, and free-cooling.

  • characterization of melting and solidification in a real scale pcm Air Heat Exchanger numerical model and experimental validation
    Energy Conversion and Management, 2011
    Co-Authors: Pablo Dolado, Ana Lazaro, Jose M Marin, Belen Zalba
    Abstract:

    Abstract This paper describes the models developed to simulate the performance of a thermal energy storage (TES) unit in a real scale PCM-Air Heat Exchanger, analyzing the Heat transfer between the Air and a commercially available and slab macroencapsulated phase change material (PCM). The models are based on one-dimensional conduction analysis, utilizing finite differences method, and implicit formulation, using the thermo-physical data of the PCM measured in the laboratory: enthalpy and thermal conductivity as functions of temperature. The models can take into account the hysteresis of the enthalpy curve and the convection inside the PCM, using effective conductivity when necessary. Two main paths are followed to accomplish the modeling: the thermal analysis of a single plate, and the thermal behavior of the entire TES unit. Comparisons between measurements and simulations are undertaken to evaluate the models. Average errors of less than 12% on thermal power are obtained for the entire cycle. Once the model is validated, a series of parameters and variables is studied to verify their influence on the behavior and design of the TES unit.

Ana Lazaro - One of the best experts on this subject based on the ideXlab platform.

  • characterization of melting and solidification in a real scale pcm Air Heat Exchanger experimental results and empirical model
    Renewable Energy, 2011
    Co-Authors: Pablo Dolado, Ana Lazaro, Jose M Marin, Belen Zalba
    Abstract:

    Abstract This paper describes the experimental studies carried out to test thermal cycling of a real-scale PCM–Air Heat Exchanger at ambient temperatures. To achieve this goal an experimental setup previously designed and used for testing real-scale prototypes of PCM–Air Heat Exchangers is modified. The PCM used is commercially available, organic, and paraffin based. The total energy exchanged during melting and solidification, as well as the time elapsed until total melting/solidification are determined from the power curves experimentally obtained. The influence of the inlet Air temperature and Air flow is studied, and results show that the continuous thermal cycling of the unit is a repetitive process: running experiments with similar conditions leads to the same thermal behavior, no degradation in the PCM properties is noticed. Pressure drop is measured for different Air flows. Depending on the inlet Air temperature, full solidification of the PCM could be achieved in less than 3 h for an 8 °C temperature difference between the inlet Air and the average phase change of the PCM. Average thermal powers of up to 4.5 kW and 3.5 kW for 1 h are obtained for melting and solidification stages, respectively. An empirical model is developed from the experimental results, which could be a useful designing tool for applications that use such technology: green housing, curing and drying processes, plant production, HVAC, and free-cooling.

  • characterization of melting and solidification in a real scale pcm Air Heat Exchanger numerical model and experimental validation
    Energy Conversion and Management, 2011
    Co-Authors: Pablo Dolado, Ana Lazaro, Jose M Marin, Belen Zalba
    Abstract:

    Abstract This paper describes the models developed to simulate the performance of a thermal energy storage (TES) unit in a real scale PCM-Air Heat Exchanger, analyzing the Heat transfer between the Air and a commercially available and slab macroencapsulated phase change material (PCM). The models are based on one-dimensional conduction analysis, utilizing finite differences method, and implicit formulation, using the thermo-physical data of the PCM measured in the laboratory: enthalpy and thermal conductivity as functions of temperature. The models can take into account the hysteresis of the enthalpy curve and the convection inside the PCM, using effective conductivity when necessary. Two main paths are followed to accomplish the modeling: the thermal analysis of a single plate, and the thermal behavior of the entire TES unit. Comparisons between measurements and simulations are undertaken to evaluate the models. Average errors of less than 12% on thermal power are obtained for the entire cycle. Once the model is validated, a series of parameters and variables is studied to verify their influence on the behavior and design of the TES unit.

  • characterization of melting and solidification in a real scale pcm Air Heat Exchanger numerical model and experimental validation
    Energy Conversion and Management, 2011
    Co-Authors: Pablo Dolado, Ana Lazaro, Jose M Mari, Ele Zalba
    Abstract:

    Abstract This paper describes the models developed to simulate the performance of a thermal energy storage (TES) unit in a real scale PCM-Air Heat Exchanger, analyzing the Heat transfer between the Air and a commercially available and slab macroencapsulated phase change material (PCM). The models are based on one-dimensional conduction analysis, utilizing finite differences method, and implicit formulation, using the thermo-physical data of the PCM measured in the laboratory: enthalpy and thermal conductivity as functions of temperature. The models can take into account the hysteresis of the enthalpy curve and the convection inside the PCM, using effective conductivity when necessary. Two main paths are followed to accomplish the modeling: the thermal analysis of a single plate, and the thermal behavior of the entire TES unit. Comparisons between measurements and simulations are undertaken to evaluate the models. Average errors of less than 12% on thermal power are obtained for the entire cycle. Once the model is validated, a series of parameters and variables is studied to verify their influence on the behavior and design of the TES unit.

  • pcm Air Heat Exchangers for free cooling applications in buildings empirical model and application to design
    Energy Conversion and Management, 2009
    Co-Authors: Ana Lazaro, Pablo Dolado, Jose M Mari, Ele Zalba
    Abstract:

    This paper presents novel design conclusions based on the experimental results and on an empirical model for a real-scale prototype of a PCM-Air Heat Exchanger. From experimental results, an empirical model was built aimed at simulating the thermal behavior in the tested Heat Exchanger in different cases. These simulations were used to evaluate the technical viability of its application. Since the thermal properties of PCM vary with temperature, a PCM-Heat Exchanger works as a transitory system and therefore, its design must be based on transitory analysis. This work shows that PCM selection criteria must include the power demand. The conclusions obtained for the PCM-Air Heat exchange can be useful for selecting PCM for other Heat Exchanger applications that use the tested geometry.

Ele Zalba - One of the best experts on this subject based on the ideXlab platform.

  • characterization of melting and solidification in a real scale pcm Air Heat Exchanger numerical model and experimental validation
    Energy Conversion and Management, 2011
    Co-Authors: Pablo Dolado, Ana Lazaro, Jose M Mari, Ele Zalba
    Abstract:

    Abstract This paper describes the models developed to simulate the performance of a thermal energy storage (TES) unit in a real scale PCM-Air Heat Exchanger, analyzing the Heat transfer between the Air and a commercially available and slab macroencapsulated phase change material (PCM). The models are based on one-dimensional conduction analysis, utilizing finite differences method, and implicit formulation, using the thermo-physical data of the PCM measured in the laboratory: enthalpy and thermal conductivity as functions of temperature. The models can take into account the hysteresis of the enthalpy curve and the convection inside the PCM, using effective conductivity when necessary. Two main paths are followed to accomplish the modeling: the thermal analysis of a single plate, and the thermal behavior of the entire TES unit. Comparisons between measurements and simulations are undertaken to evaluate the models. Average errors of less than 12% on thermal power are obtained for the entire cycle. Once the model is validated, a series of parameters and variables is studied to verify their influence on the behavior and design of the TES unit.

  • pcm Air Heat Exchangers for free cooling applications in buildings empirical model and application to design
    Energy Conversion and Management, 2009
    Co-Authors: Ana Lazaro, Pablo Dolado, Jose M Mari, Ele Zalba
    Abstract:

    This paper presents novel design conclusions based on the experimental results and on an empirical model for a real-scale prototype of a PCM-Air Heat Exchanger. From experimental results, an empirical model was built aimed at simulating the thermal behavior in the tested Heat Exchanger in different cases. These simulations were used to evaluate the technical viability of its application. Since the thermal properties of PCM vary with temperature, a PCM-Heat Exchanger works as a transitory system and therefore, its design must be based on transitory analysis. This work shows that PCM selection criteria must include the power demand. The conclusions obtained for the PCM-Air Heat exchange can be useful for selecting PCM for other Heat Exchanger applications that use the tested geometry.

G N Tiwari - One of the best experts on this subject based on the ideXlab platform.

  • stand alone photovoltaic pv integrated with earth to Air Heat Exchanger eahe for space Heating cooling of adobe house in new delhi india
    Energy Conversion and Management, 2010
    Co-Authors: Arvind Chel, G N Tiwari
    Abstract:

    Abstract This paper deals with an experimental outdoor annual performance evaluation of 2.32 kW P photovoltaic (PV) power system located at solar energy park in New Delhi composite climatic conditions. This PV system operates the daily electrical load nearly 10 kW h/day which comprises of various applications such as electric Air blower of an earth to Air Heat Exchanger (EAHE) used for Heating/cooling of adobe house, ceiling fan, fluorescent tube-light, computer, submersible water pump, etc. The outdoor efficiencies, power generated and lost in PV system components were determined using hourly experimental measured data for 1 year on typical clear day in each month. These realistic data are useful for design engineers for outdoor assessment of PV system components. The energy conservation, mitigation of CO 2 emission and carbon credit potential of the existing PV integrated EAHE system is presented in this paper. Also, the energy payback time (EPBT) and unit cost of electricity were determined for both stand-alone PV (SAPV) and building roof integrated PV (BIPV) systems.

  • theoretical performance assessment of an integrated photovoltaic and earth Air Heat Exchanger greenhouse using energy and exergy analysis methods
    Energy and Buildings, 2009
    Co-Authors: Sujata Nayak, G N Tiwari
    Abstract:

    Abstract In this paper, a simplified mathematical model develops to study round the year effectiveness of photovoltaic/thermal (PV/T) and earth Air Heat Exchanger (EAHE) integrated with a greenhouse, located at IIT Delhi, India. The solar energy application through photovoltaic system and earth Air Heat Exchanger (EAHE) for Heating and cooling of a greenhouse is studied with the help of this simplified mathematical model. Calculations are done for four types of weather conditions (a, b, c and d types) in New Delhi, India. The paper compares greenhouse Air temperatures when it is operated with photovoltaic/thermal (PV/T) during daytime coupled with earth Air Heat Exchanger (EAHE) at night, with Air temperatures when it is operated exclusively with photovoltaic/thermal system (PV/T) and earth Air Heat Exchanger (EAHE), for 24 h. The results reveal that Air temperature inside the greenhouse can be increased by around 7–8 °C during winter season, when the system is operated with photovoltaic (PV/T), coupled with earth Air Heat Exchanger (EAHE) at night. From the results, it is seen that the hourly useful thermal energy generated, during daytime and night, when the system is operated with photovoltaic (PV/T) coupled with earth Air Heat Exchanger (EAHE), is 33 MJ and 24.5 MJ, respectively. The yearly thermal energy generated by the system has been calculated to be 24728.8 kWh, while the net electrical energy savings for the year is 805.9 kWh and the annual thermal exergy energy generated is 1006.2 kWh.

  • performance evaluation and life cycle cost analysis of earth to Air Heat Exchanger integrated with adobe building for new delhi composite climate
    Energy and Buildings, 2009
    Co-Authors: Arvind Chel, G N Tiwari
    Abstract:

    Abstract This paper aims to develop thermal model of a vault roof building integrated with earth to Air Heat Exchanger (EAHE). The building under consideration is made of brick vault and adobe (or mud) structures. The methodology adopted for developing thermal model of this building with six interconnected rooms is presented in this paper. The energy balance equations were solved simultaneously using fourth order Runge–Kutta numerical technique. The results from the thermal model were validated using experimental observed data. Experimental results showed that the room Air temperature during winter was found 5–15 °C higher as compared to ambient Air temperature while lower during summer months. The results show that annual energy saving potential of the building before and after integration of EAHE were 4946 kWh/year and 10321 kWh/year respectively. The seasonal energy efficiency ratio (SEER) for EAHE was determined as 2–3. This considerable increase in annual energy savings potential of building due to EAHE leads to mitigation of CO2 emissions about 16 tons/year and the corresponding annual carbon credit of building was estimated as € 340/year. The life cycle cost (LCC) analysis shows that the payback period is less than 2 years for the investment on EAHE system.

  • modeling and parametric studies for thermal performance of an earth to Air Heat Exchanger integrated with a greenhouse
    Energy Conversion and Management, 2006
    Co-Authors: M K Ghosal, G N Tiwari
    Abstract:

    Abstract A thermal model has been developed to investigate the potential of using the stored thermal energy of the ground for greenhouse Heating and cooling with the help of an earth to Air Heat Exchanger (EAHE) system integrated with the greenhouse located in the premises of IIT, Delhi, India. Experiments were conducted extensively throughout the year 2003, but the developed model was validated against typical clear and sunny days experiments. Parametric studies performed for the EAHE coupled with the greenhouse illustrate the effects of buried pipe length, pipe diameter, mass flow rate of Air, depth of ground and types of soil on the greenhouse Air temperatures. The temperatures of the greenhouse Air, with the experimental parameters of the EAHE, were found to be, on average 7–8 °C higher in the winter and 5–6 °C lower in the summer than those of the same greenhouse without the EAHE. The greenhouse Air temperatures increase in the winter and decrease in the summer with increasing pipe length, decreasing pipe diameter, decreasing mass flow rate of flowing Air inside buried pipe and increasing depth of ground up to 4 m. The predicted and measured values of the greenhouse Air temperatures that were verified, in terms of root mean square percent deviation and correlation coefficient, exhibited fAir agreement.

  • modeling and comparative thermal performance of ground Air collector and earth Air Heat Exchanger for Heating of greenhouse
    Energy and Buildings, 2005
    Co-Authors: M K Ghosal, G N Tiwari, K P Pandey
    Abstract:

    The potential of using the stored thermal energy of ground for space Heating has been investigated with the help of two buried pipe systems, i.e., ground Air collector and earth Air Heat Exchanger, integrated with the greenhouse located in the premises of Indian Institute of Technology, Delhi, India. The total length of the buried pipes in both the arrangements was kept same for making a comparative study. A complete numerical model has been developed to predict and compare their thermal performance for choosing a suitable Heating method in the composite climate of India. Experiments were conducted extensively during winter period from November 2002 to March 2003, but the model was validated against the clear and sunny days. Performance of these two arrangements was compared in terms of thermal load leveling and total Heating potential. Temperatures of greenhouse Air with ground Air collector were observed to be 2-3 8C higher than those with earth Air Heat Exchanger. The temperature fluctuations of greenhouse Air were also less when operated with ground Air collector as compared to earth Air Heat Exchanger. Predicted and computed values of greenhouse Air temperatures in both the systems exhibited fAir agreement. Finally ground Air collector was chosen as a suitable option for Heating of greenhouse in the above climate.