Operating optimization for improved energy consumption of a TAC system affected by nighttime thermal loads of building envelopes

Abstract Task/ambient air conditioning (TAC) system is reported to be an energy efficient technology with available methods to control thermal comfortable level for sleeping environments. Better performance in energy saving for TAC systems in sleeping environment has been demonstrated in previous studies. However, it should be noticed that the building envelope thermal load affects the indoor thermal environment and operation of the air conditioning system due to the heat transfer through the envelope. The variation of indoor thermal environment will directly affect the performance of the TAC system, especially the set of operation parameters. Therefore, an optimization study on the TAC system operation considering the effects of envelope thermal load was carried out in this paper. Firstly, a full factorial design method was used to construct the simulation case matrix. Secondly, the models of the energy consumption and thermal comfort were established using operating parameters and envelope thermal load. Thirdly, comfort surface and comfort lines were obtained to calculate the optimum operating parameters at which the energy consumption was at the lowest. Finally, the energy consumption at the optimum status was calculated. The results show that the TAC system at the optimum status can save 1.4 to 1.7 kWh each night.

[1]  Lina Yang,et al.  Cooling load reduction by using thermal mass and night ventilation , 2008 .

[2]  D. Shiming,et al.  Computational fluid dynamics (CFD) modelling of air flow field, mean age of air and CO2 distributions inside a bedroom with different heights of conditioned air supply outlet , 2016 .

[3]  Dongmei Pan,et al.  Computational fluid dynamics analysis of convective heat transfer coefficients for a sleeping human body , 2017 .

[4]  Mao Ning,et al.  Experimental and numerical studies on the performance evaluation of a bed-based task/ambient air conditioning (TAC) system , 2014 .

[5]  Ali Malkawi,et al.  Defining the Influence Region in neighborhood-scale CFD simulations for natural ventilation design , 2016 .

[6]  Shiming Deng,et al.  A questionnaire survey on sleeping thermal environment and bedroom air conditioning in high-rise residences in Hong Kong , 2006 .

[7]  Zhiqiang Zhai,et al.  Application of Computational Fluid Dynamics in Building Design: Aspects and Trends , 2006 .

[8]  Wontae Kim,et al.  Thermal characteristics of a personal environment module task air conditioning system: an experimental study , 2001 .

[9]  Dongmei Pan,et al.  Performance evaluation of an air conditioning system with different heights of supply outlet applied to a sleeping environment , 2014 .

[10]  Shinichi Tanabe,et al.  Thermal sensation and comfort with different task conditioning systems , 2007 .

[11]  F. Menter.  Two-equation eddy-viscosity turbulence models for engineering applications , 1994 .

[12]  Zhao Zhang,et al.  Evaluation of Various Turbulence Models in Predicting Airflow and 1 Turbulence in Enclosed Environments by CFD : Part-1 : 2 Summary of Prevalent Turbulence Models 3 4 , 2007 .

[13]  Eusébio Z. E. Conceição,et al.  Evaluation of comfort level in desks equipped with two personalized ventilation systems in slightly warm environments , 2010 .

[14]  Dongmei Pan,et al.  A numerical study on influences of building envelope heat gain on operating performances of a bed-based task/ambient air conditioning (TAC) system in energy saving and thermal comfort , 2017 .

[15]  Dongmei Pan,et al.  Performance evaluation of a novel bed-based task/ambient conditioning (TAC) system , 2012 .

[16]  Dongmei Pan,et al.  Thermal, ventilation and energy saving performance evaluations of a ductless bed-based task/ambient air conditioning (TAC) system , 2013 .

[17]  D. Wyon,et al.  The Acceptable Air Velocity Range for Local Air Movement in The Tropics , 2006 .

[18]  Qingyan Chen,et al.  A Procedure for Verification, Validation, and Reporting of Indoor Environment CFD Analyses , 2002 .

[19]  Jianlei Niu,et al.  Experimental study on a chair-based personalized ventilation system , 2007 .

[20]  Luisa F. Cabeza,et al.  Economic impact of integrating PCM as passive system in buildings using Fanger comfort model , 2016 .

[21]  Anastasios I. Stamou,et al.  Verification of a CFD model for indoor airflow and heat transfer , 2006 .

[22]  Shiming Deng,et al.  Application of TOPSIS method in evaluating the effects of supply vane angle of a task/ambient air conditioning system on energy utilization and thermal comfort , 2016 .

[23]  Pan Dongmei,et al.  Air-conditioning for sleeping environments in tropics and/or sub-tropics - a review , 2013 .

[24]  Chandra Sekhar,et al.  Energy analysis of the personalized ventilation system in hot and humid climates , 2010 .

[25]  Dongmei Pan,et al.  Experimental and numerical study on air flow and moisture transport in sleeping environments with a task/ambient air conditioning (TAC) system , 2016 .

[26]  Muhsin Kilic,et al.  Numerical analysis of air flow, heat transfer, moisture transport and thermal comfort in a room heat , 2011 .

[27]  G. D. Raithby,et al.  A Finite-Volume Method for Predicting a Radiant Heat Transfer in Enclosures With Participating Media , 1990 .

[28]  Shiming Deng,et al.  A study on the thermal comfort in sleeping environments in the subtropics : Developing a thermal comfort model for sleeping environments , 2008 .

[29]  Shiming Deng,et al.  A study on the characteristics of nighttime bedroom cooling load in tropics and subtropics , 2004 .

[30]  Mengjie Song,et al.  An experimental study on defrosting performance of an air source heat pump unit with a multi-circuit outdoor coil at different frosting evenness values , 2016 .

[31]  P. J. Jones,et al.  Computational fluid dynamics for building air flow prediction—current status and capabilities , 1992 .

[32]  Arsen Krikor Melikov,et al.  Seat headrest-incorporated personalized ventilation: Thermal comfort and inhaled air quality , 2012 .

[33]  J P Libert,et al.  Sweating responses and body temperatures during nocturnal sleep in humans. , 1987, The American journal of physiology.

[34]  Guangcai Gong,et al.  Experimental investigation on an air source heat pump unit with a three-circuit outdoor coil for its reverse cycle defrosting termination temperature , 2017 .

[35]  Hui Zhang,et al.  Testing and optimizing the performance of a floor-based task conditioning system , 1995 .