Impact of summer office set air-conditioning temperature on energy consumption and thermal comfort

To explore the relationship between summer office set air-conditioning temperature and energy consumption related to air conditioning use to provide human thermal comfort,a comparison experiment was conducted in three similar offices at temperatures of 24,26 and 28 ℃ respectively. A thermal comfort questionnaire survey was conducted. It is demonstrated that air-conditioner energy consumption at the set temperature of 28 ℃ is 113% and 271% lower than at 26 ℃ and 24 ℃,respectively. A linear relationship exists between air-conditioner energy consumption and the indoor and outdoor temperature difference. When comfortably dressed,over 80% of research participants accept the set temperature of 28 ℃. The regression analysis leads to a neutral temperature of 26.2 ℃ and an acceptable temperature of 28.2 ℃ for over 80% of the research participants subjects,indicating that the current 26 ℃ set temperature for offices in summer,required by Chinese General Office of the State Council,can be increased to 28 ℃. Moreover,analysis of predicted mean vote(PMV) index shows that a set temperature of 27 ℃,not 26 ℃,is sufficiently comfortable for office staff wearing long-sleeve shirts,long pants and leather shoes.

Influence of Surrounding Structures upon the Aerodynamic and Acoustic Performance of the Outdoor Unit of a Split Air-Conditioner

DC-inverter split air-conditioner is widely used in Chinese homes as a result of its high-efficiency and energy-saving. Recently, the researches on its outdoor unit have focused on the influence of surrounding structures upon the aerodynamic and acoustic performance, however they are only limited to the influence of a few parameters on the performance, and practical design of the unit requires more detailed parametric analysis. Three-dimensional computational fluid dynamics（CFD） and computational aerodynamic acoustics（CAA） simulation based on FLUENT solver is used to study the influence of surrounding structures upon the aforementioned properties of the unit. The flow rate and sound pressure level are predicted for different rotating speed, and agree well with the experimental results. The parametric influence of three main surrounding structures（i.e. the heat sink, the bell-mouth type shroud and the outlet grille） upon the aerodynamic performance of the unit is analyzed thoroughly. The results demonstrate that the tip vortex plays a major role in the flow fields near the blade tip and has a great effect on the flow field of the unit. The inlet ring＇s size and throat＇s depth of the bell-mouth type shroud, and the through-flow area and configuration of upwind and downwind sections of the outlet grille are the most important factors that affect the aerodynamic performance of the unit. Furthermore, two improved schemes against the existing prototype of the unit are developed, which both can significantly increase the flow rate more than 6 %（i.e. 100 m3·h～（-1）） at given rotating speeds. The inevitable increase of flow noise level when flow rate is increased and the advantage of keeping a lower rotating speed are also discussed. The presented work could be a useful guideline in designing the aerodynamic and acoustic performance of the split air-conditioner in engineering practice.

Effect of air-conditioner exposure on semen quality

Aim: To investigate the effect of air-conditioner exposure on semen quality. Methods: The data came from the healthy male volunteers, aged 22 to 30 years, who went to centers for maternity and children health for premarital physical examination in Shanghai, Henan, Zhejiang and Hebei from December 1998 to February 2000. The sampling size is 304. Results: Among the subjects, 90 (29.6 %) had air-conditioner at home and the rest did not. X2-test and multiple logistic regression analyses showed that, the difference between the exposure and control groups was statistically significant in semen volume, sperm density and proportion of sperm with normal morphology. The three indexes were lower in the exposure group. Conclusion: Air-conditioner exposure possibly influences the semen quality.

KOF(Z)DI8II and KQF(Z)D24II automobile air-conditioner

TheYueyangHengliRefrigeratingEquipmentCo.Ltd.inHunanProvinceobtainedin1997itsIS09001certificationfromChinaandGermanYTheKQF(Z)D2411automobileair-conditioneriscomposedoftWoparts,itscoldvolumeis24KWandcanbeusedforpassengercarswith5to60seats.Theproductsi...

Deploying a Deep Learning-based Application for an Efficient Ther­mal Energy Storage Air-Conditioning(TES-AC)System:Design Guidelines

Facility management and maintenance of the Thermal-Energy-Storage Air-Conditioning(TES-AC)system is a tedious task at a large scale mainly due to the charging load that can increase energy consumption if needed to be charged at peak hours.Besides,maintenance of TES-AC at a large scale gets complex as it contains many sensor data.By utilizing deep learning techniques on the sensor data,charging load prediction can be made possible,so facility managers can prepare in advance.However,a deep learning-based application will be unusable if it is not deployed in a user-friendly manner where facility managers can benefit from this application.Hence,this research focuses on gathering design guidelines for a deep learning-based application and further validates the design considerations with a developed application for efficient human-computer interaction through qualitative analysis.The approach taken to gather design guidelines demonstrated a positive correlation between expert-suggested features and the user-friendly aspect of the application as 67.08%of participants found the features suggested by experts to be most satisfactory.Furthermore,it evaluates user satisfaction with the advanced developed application for TES-AC according to the gathered design guidelines.

Design of ionic liquids as liquid desiccant for an air conditioning system

Suitable control of the humidity can contribute to electric energy savings. However, the present dehumidification system has many weak points. The liquid desiccant air-conditioning system has recently gained growing interest from the stand point of reducing energy consumption during dehumidification. In order to find the appropriate ionic liquids(ILs) as a desiccant for the liquid desiccant air-conditioner system, we conducted a systematic evaluation of the humidification capability of 16 types of ILs. Among the tested ILs, tributyl(methyl)phosphonium dimethyl phosphate([P4441][DMPO_4]) exhibited the best dehumidification capacity and had a less corrosive effect on four types of metals as possible piping materials. It should be noted that this [P_(4441)][DMPO_4] has a very stable nature and produced no odor while conducting the experiment and storing for over 1 year at room temperature under ambient conditions. Furthermore, it was revealed that a 77%(w/w) aqueous solution of [P4441][DMPO_4] worked as an efficient desiccant liquid for the liquid desiccant air-conditioner system.

Thermodynamic Analysis and Experimental Research of Water-Cooled Small Space Thermoelectric Air-Conditioner

This paper aims to find a more general analysis method for the refrigeration performance,and to design a high efficiency modular cooling structure of water-cooled plate.A new analysis method,namely current and refrigeration rate density analysis,is proposed.The general refrigeration performance calculation equations are obtained.A finite-time thermodynamic model of the thermoelectric device is established considering Thomson effect.The basic structure of water-cooled thermoelectric air-conditioner is designed and the specific calculation method is given.The influences of input current density,filling factor and heat transfer conditions on refrigeration performance of the thermoelectric air-conditioner are analyzed,which is compared with refrigeration performance of air-cooled thermoelectric air-conditioner.The results show that the maximum refrigeration rate density of the water-cooled thermoelectric air-conditioner is 8.65 k W/m^(2),and the maximum coefficient of performance(COP)is 2.27 in the case of the cooling temperature differenceΔT=5 K.Compared withΔT=5 K,the maximum refrigeration rate density and the maximum COP ofΔT=15 K decreases by 27.98%and 76.65%,respectively.At the filling factorθ=0.43,the refrigeration rate density and COP are 2.57 k W/m~2 and 1.24,respectively.The experimental device of thermoelectric air-conditioner is established to verify the model.The experimental results show that the maximum value of input current and COP is 4 A and 0.95 with the efficient water-cooling method,respectively.The experimental data coincides with the theoretical calculation,which shows the validity of the analysis method and cooling method.

Technologies and Practical Implementations of Air-conditioner Based Demand Response

Nowadays,the most notable uncertainty for an electricity utility lies in the electrical demand of end-users.Demand response(DR)has acquired considerable attention due to uncertain generation outputs from intermittent renewable energy sources and advancements of smart grid technologies.The percentage of the air-conditioner(AC)load over the total load demand in a building is usually very high.Therefore,controlling the power demand of ACs is one of significant measures for implementing DR.In this paper,the increasing development of ACs,and their impacts on power demand are firstly introduced,with an overview of possible DR programs.Then,a comprehensive review and discussion on control techniques and DR programs for ACs to manage electricity utilization in residential and commercial energy sectors are carried out.Next,comparative analysis among various programs and projects utilized in different countries for optimizing electricity consumption by ACs is presented.Finally,the conclusions along with future recommendations and challenges for optimal employment of ACs are presented in the perspective of power systems.

Design of quaternary ammonium type-ionic liquids as desiccants for an air-conditioning system

The liquid desiccant air-conditioning system allows reducing energy consumption compared to the conventional compressor-type air conditioners.In order to develop desiccant materials for air conditioners,we have investigated the dehumidification capability of quaternary ammonium Ionic Liquids(ILs)and the equilibrium water vapor pressure of aqueous solutions of these ammonium salts.Among the seven tested types of ILs,2-hydroxyN,N,N-trimethylethan-1-aminium dimethylphosphate([Ch][DMPO4])displayed the best dehumidification capability and the lowest equilibrium water vapor pressure.Furthermore,the 80%aqueous solution of[Ch][DMPO4]exhibited a less corrosive effect on four types of metals,i.e.,steel(hot dip zinc-aluminum alloy plated steel),copper(C1100P),aluminum(A5052),and stainless steel(SUS:SUS304).It should be noted that this[Ch][DMPO4]is not only non-toxic but also exhibits a stable nature;the aqueous solution produced no odor after storing for over 1 year under ambient conditions.

Analysis of indoor set-point temperature of split-type ACs on thermal comfort and energy savings for office buildings in hot-humid climates

In hot-humid climates,particularly in sub-Saharan Africa(SSA),ambient temperatures and relative humidity are as high as 35°C and 84%,respectively,requiring the use of mechanical cooling systems for indoor thermal comfort.Split-type vapor-compression air-conditioners(SVAC)are mainly used for space cooling in SSA and consume 60-80%of total energy consumption in commercial and public buildings.Appropriate control strategy of the indoor set-point temperature of SVAC can result in significant energy savings in these buildings.In this study,modeling and dynamic simulation have been conducted using EnergyPlus to predict the energy saving potential and indoor thermal comfort of buildings in hot-humid climates by controlling set-point temperature of the SVAC.In a case study,climatic data for Ghana,was used to predict the energy saving potential and indoor thermal comfort.The study results revealed that,to ensure indoor thermal comfort at high outdoor temperature condition of 35°C,the least and optimum set-point temperatures of the SVAC should be 21°C and 25°C,respectively.On the other hand,for low outdoor temperature condition,the least and optimum set-point temperatures were 22°C and 26°C,respectively.Considering 1-star and 2-star rated SVACs which are dominantly used in Ghana,operating at 21-25°C in the case of high outdoor conditions,and 22-26°C for low outdoor conditions relative to the least temperatures resulted in energy savings of 8-33%and 12-44%,respectively.

Indoor environment of nearly zero energy residential buildings with conventional air conditioning in hot-summer and cold-winter zone

According to the few researches on Nearly zero energy residential buildings(NZERB)in hot-summer and cold-winter zone,although it could reduce the cooling load of buildings due to its high thermal insulation and air tightness,it still needed for certain cooling in summer.This paper studied indoor environment of NZERB un-der three kinds of air-conditioners(split-type air-conditioner,multi-line air-conditioner and ceiling radiant air-conditioner).Firstly,a simulation model of NZERB was established based on Nanjing,a typical city in hot-summer and cold-winter zone.Secondly,variation of indoor air temperature and building load characteristics with outdoor air temperature were studied.Thirdly,indoor environment and energy consumption under three selected con-ventional air-conditioners in summer were simulated.Finally,the discussion was given,and an air-conditioner combining with convective and radiant cooling were proposed.The results indicated that the air-conditioner needed to be turned on in NZERB in hot-summer and cold-winter zone due to the room air temperature in off-air condition ranged from 32℃to 36℃,which was higher than designed indoor environment temperature in sum-mer,but the indoor environment of NZERB under three selected conventional air-conditioners could not meet the requirements of energy saving and comfort at the same time,and a proposed convective-radiant air-conditioner could be fast,stable,and energy saving.The findings can provide a reference for conducting active technology in NZERB.