The Experts below are selected from a list of 105675 Experts worldwide ranked by ideXlab platform

Chunlu Zhang - One of the best experts on this subject based on the ideXlab platform.

  • dynamic simulation of air to water dual mode heat pump with screw compressor
    Applied Thermal Engineering, 2003
    Co-Authors: Long Fu, Guoliang Ding, Chunlu Zhang
    Abstract:

    Abstract A dynamic model of air-to-water dual-mode heat pump with screw compressor is presented here. The high-pressure and low-pressure segments are divided into three control volumes, including the refrigerant inside tube, the tube wall and the fluid outside tube that is water or air. Time dependent ordinary differential equations are obtained from the mass and energy balances for each control volume. As the compressor, thermostatic expansion valve (TEV) body, and reversing valve have very small thermal inertias, steady-state models are applied for the compression, throttling, and leakage processes. The relationship between the temperature of the saturated liquid–vapor mixture in TEV’s bulb and the temperature of the refrigerant vapor at the evaporator exit is described with a time dependent ordinary differential equation. System simulation is finally carried out with ‘predictor–corrector’ and ‘adaptive Integration Step’ methods. Simulated results are in good agreement with the measured data, which lead to conclusion that the model can be used as a tool for the product development.

  • dynamic simulation of air to water dual mode heat pump with screw compressor
    Applied Thermal Engineering, 2003
    Co-Authors: Long Fu, Guoliang Ding, Chunlu Zhang
    Abstract:

    Abstract A dynamic model of air-to-water dual-mode heat pump with screw compressor is presented here. The high-pressure and low-pressure segments are divided into three control volumes, including the refrigerant inside tube, the tube wall and the fluid outside tube that is water or air. Time dependent ordinary differential equations are obtained from the mass and energy balances for each control volume. As the compressor, thermostatic expansion valve (TEV) body, and reversing valve have very small thermal inertias, steady-state models are applied for the compression, throttling, and leakage processes. The relationship between the temperature of the saturated liquid–vapor mixture in TEV’s bulb and the temperature of the refrigerant vapor at the evaporator exit is described with a time dependent ordinary differential equation. System simulation is finally carried out with ‘predictor–corrector’ and ‘adaptive Integration Step’ methods. Simulated results are in good agreement with the measured data, which lead to conclusion that the model can be used as a tool for the product development.

Long Fu - One of the best experts on this subject based on the ideXlab platform.

  • dynamic simulation of air to water dual mode heat pump with screw compressor
    Applied Thermal Engineering, 2003
    Co-Authors: Long Fu, Guoliang Ding, Chunlu Zhang
    Abstract:

    Abstract A dynamic model of air-to-water dual-mode heat pump with screw compressor is presented here. The high-pressure and low-pressure segments are divided into three control volumes, including the refrigerant inside tube, the tube wall and the fluid outside tube that is water or air. Time dependent ordinary differential equations are obtained from the mass and energy balances for each control volume. As the compressor, thermostatic expansion valve (TEV) body, and reversing valve have very small thermal inertias, steady-state models are applied for the compression, throttling, and leakage processes. The relationship between the temperature of the saturated liquid–vapor mixture in TEV’s bulb and the temperature of the refrigerant vapor at the evaporator exit is described with a time dependent ordinary differential equation. System simulation is finally carried out with ‘predictor–corrector’ and ‘adaptive Integration Step’ methods. Simulated results are in good agreement with the measured data, which lead to conclusion that the model can be used as a tool for the product development.

  • dynamic simulation of air to water dual mode heat pump with screw compressor
    Applied Thermal Engineering, 2003
    Co-Authors: Long Fu, Guoliang Ding, Chunlu Zhang
    Abstract:

    Abstract A dynamic model of air-to-water dual-mode heat pump with screw compressor is presented here. The high-pressure and low-pressure segments are divided into three control volumes, including the refrigerant inside tube, the tube wall and the fluid outside tube that is water or air. Time dependent ordinary differential equations are obtained from the mass and energy balances for each control volume. As the compressor, thermostatic expansion valve (TEV) body, and reversing valve have very small thermal inertias, steady-state models are applied for the compression, throttling, and leakage processes. The relationship between the temperature of the saturated liquid–vapor mixture in TEV’s bulb and the temperature of the refrigerant vapor at the evaporator exit is described with a time dependent ordinary differential equation. System simulation is finally carried out with ‘predictor–corrector’ and ‘adaptive Integration Step’ methods. Simulated results are in good agreement with the measured data, which lead to conclusion that the model can be used as a tool for the product development.

Christoph Dellago - One of the best experts on this subject based on the ideXlab platform.

  • an enhanced version of the heat exchange algorithm with excellent energy conservation properties
    Journal of Chemical Physics, 2015
    Co-Authors: Peter Wirnsberger, Daan Frenkel, Christoph Dellago
    Abstract:

    We propose a new algorithm for non-equilibrium molecular dynamics simulations of thermal gradients. The algorithm is an extension of the heat exchange algorithm developed by Hafskjold et al. [Mol. Phys. 80, 1389 (1993); 81, 251 (1994)], in which a certain amount of heat is added to one region and removed from another by rescaling velocities appropriately. Since the amount of added and removed heat is the same and the dynamics between velocity rescaling Steps is Hamiltonian, the heat exchange algorithm is expected to conserve the energy. However, it has been reported previously that the original version of the heat exchange algorithm exhibits a pronounced drift in the total energy, the exact cause of which remained hitherto unclear. Here, we show that the energy drift is due to the truncation error arising from the operator splitting and suggest an additional coordinate Integration Step as a remedy. The new algorithm retains all the advantages of the original one whilst exhibiting excellent energy conservation as illustrated for a Lennard-Jones liquid and SPC/E water.

  • an enhanced version of the heat exchange algorithm with excellent energy conservation properties
    Journal of Chemical Physics, 2015
    Co-Authors: Peter Wirnsberger, Daan Frenkel, Christoph Dellago
    Abstract:

    We propose a new algorithm for non-equilibrium molecular dynamics simulations of thermal gradients. The algorithm is an extension of the heat exchange algorithm developed by Hafskjold et al. [Mol. Phys. 80, 1389 (1993); 81, 251 (1994)], in which a certain amount of heat is added to one region and removed from another by rescaling velocities appropriately. Since the amount of added and removed heat is the same and the dynamics between velocity rescaling Steps is Hamiltonian, the heat exchange algorithm is expected to conserve the energy. However, it has been reported previously that the original version of the heat exchange algorithm exhibits a pronounced drift in the total energy, the exact cause of which remained hitherto unclear. Here, we show that the energy drift is due to the truncation error arising from the operator splitting and suggest an additional coordinate Integration Step as a remedy. The new algorithm retains all the advantages of the original one whilst exhibiting excellent energy conservation as illustrated for a Lennard-Jones liquid and SPC/E water.

Guoliang Ding - One of the best experts on this subject based on the ideXlab platform.

  • dynamic simulation of air to water dual mode heat pump with screw compressor
    Applied Thermal Engineering, 2003
    Co-Authors: Long Fu, Guoliang Ding, Chunlu Zhang
    Abstract:

    Abstract A dynamic model of air-to-water dual-mode heat pump with screw compressor is presented here. The high-pressure and low-pressure segments are divided into three control volumes, including the refrigerant inside tube, the tube wall and the fluid outside tube that is water or air. Time dependent ordinary differential equations are obtained from the mass and energy balances for each control volume. As the compressor, thermostatic expansion valve (TEV) body, and reversing valve have very small thermal inertias, steady-state models are applied for the compression, throttling, and leakage processes. The relationship between the temperature of the saturated liquid–vapor mixture in TEV’s bulb and the temperature of the refrigerant vapor at the evaporator exit is described with a time dependent ordinary differential equation. System simulation is finally carried out with ‘predictor–corrector’ and ‘adaptive Integration Step’ methods. Simulated results are in good agreement with the measured data, which lead to conclusion that the model can be used as a tool for the product development.

  • dynamic simulation of air to water dual mode heat pump with screw compressor
    Applied Thermal Engineering, 2003
    Co-Authors: Long Fu, Guoliang Ding, Chunlu Zhang
    Abstract:

    Abstract A dynamic model of air-to-water dual-mode heat pump with screw compressor is presented here. The high-pressure and low-pressure segments are divided into three control volumes, including the refrigerant inside tube, the tube wall and the fluid outside tube that is water or air. Time dependent ordinary differential equations are obtained from the mass and energy balances for each control volume. As the compressor, thermostatic expansion valve (TEV) body, and reversing valve have very small thermal inertias, steady-state models are applied for the compression, throttling, and leakage processes. The relationship between the temperature of the saturated liquid–vapor mixture in TEV’s bulb and the temperature of the refrigerant vapor at the evaporator exit is described with a time dependent ordinary differential equation. System simulation is finally carried out with ‘predictor–corrector’ and ‘adaptive Integration Step’ methods. Simulated results are in good agreement with the measured data, which lead to conclusion that the model can be used as a tool for the product development.

Peter Wirnsberger - One of the best experts on this subject based on the ideXlab platform.

  • an enhanced version of the heat exchange algorithm with excellent energy conservation properties
    Journal of Chemical Physics, 2015
    Co-Authors: Peter Wirnsberger, Daan Frenkel, Christoph Dellago
    Abstract:

    We propose a new algorithm for non-equilibrium molecular dynamics simulations of thermal gradients. The algorithm is an extension of the heat exchange algorithm developed by Hafskjold et al. [Mol. Phys. 80, 1389 (1993); 81, 251 (1994)], in which a certain amount of heat is added to one region and removed from another by rescaling velocities appropriately. Since the amount of added and removed heat is the same and the dynamics between velocity rescaling Steps is Hamiltonian, the heat exchange algorithm is expected to conserve the energy. However, it has been reported previously that the original version of the heat exchange algorithm exhibits a pronounced drift in the total energy, the exact cause of which remained hitherto unclear. Here, we show that the energy drift is due to the truncation error arising from the operator splitting and suggest an additional coordinate Integration Step as a remedy. The new algorithm retains all the advantages of the original one whilst exhibiting excellent energy conservation as illustrated for a Lennard-Jones liquid and SPC/E water.

  • an enhanced version of the heat exchange algorithm with excellent energy conservation properties
    Journal of Chemical Physics, 2015
    Co-Authors: Peter Wirnsberger, Daan Frenkel, Christoph Dellago
    Abstract:

    We propose a new algorithm for non-equilibrium molecular dynamics simulations of thermal gradients. The algorithm is an extension of the heat exchange algorithm developed by Hafskjold et al. [Mol. Phys. 80, 1389 (1993); 81, 251 (1994)], in which a certain amount of heat is added to one region and removed from another by rescaling velocities appropriately. Since the amount of added and removed heat is the same and the dynamics between velocity rescaling Steps is Hamiltonian, the heat exchange algorithm is expected to conserve the energy. However, it has been reported previously that the original version of the heat exchange algorithm exhibits a pronounced drift in the total energy, the exact cause of which remained hitherto unclear. Here, we show that the energy drift is due to the truncation error arising from the operator splitting and suggest an additional coordinate Integration Step as a remedy. The new algorithm retains all the advantages of the original one whilst exhibiting excellent energy conservation as illustrated for a Lennard-Jones liquid and SPC/E water.