Designing, Modelling And Experimental Investigation Of Direct Evaporative Cooling System Coupled With Commercial Desiccant Dehumidifier

2021 ◽  
pp. 1-16
Author(s):  
Abdul Basit ◽  
Mariam Mahmood ◽  
Adeel Waqas ◽  
Majid Ali ◽  
Waqas Khalid
Keyword(s):  
Relative Humidity ◽  
Thermal Comfort ◽  
Flow Rate ◽  
System Performance ◽  
Evaporative Cooling ◽  
Comfort Level ◽  
Electric Heater ◽  
Air Cooling ◽  
Human Thermal Comfort ◽  
Direct Evaporative Cooling

Abstract With the rising demand of clean and energy efficient air conditioning systems, evaporative air cooling technique is gaining significant attention owing to less energy consumption and environmentally safe technology in comparison with conventional refrigerants based air conditioners. In this study, commercial desiccant dehumidifier is coupled with experimentally developed Direct Evaporative Cooling (DEC) system in order to first dehumidify the air, and then pass it through DEC to achieve human thermal comfort level defined by ASHRAE standards. Under the climatic conditions of Islamabad-Pakistan, multiple experiments were carried out at different temperatures, flow rate and relative humidity of air during November, when air temperature and relative humidity was in the range of 25-30°C and 40%-60%, respectively. In order to analyze the system performance under summer ambient conditions, indoor temperature was increased by 8-10°C and relative humidity by 15%-25% in laboratory. Experimental analysis showed that the system can provide human comfort level for a range of temperature 29-39.7°C and relative humidity of 65-80% at flow rate of 180 m3/hr. In order to achieve thermal comfort at higher humidity level, DEC is coupled with commercial desiccant dehumidifier. However, due to desiccant regeneration by an electric heater in the dehumidifier, the overall power consumption of the whole system rises up to 1.95 kW. Two well-known indices Coefficient of Performance (CoP) and Energy Efficiency Ratio (EER) are used to analyze the system performance.

scholarly journals Study of Human Thermal Comfort for Cyber–Physical Human Centric System in Smart Homes

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 372 ◽  
Author(s):  
Yuan Fang ◽  
Yuto Lim ◽  
Sian En Ooi ◽  
Chenmian Zhou ◽  
Yasuo Tan
Keyword(s):  
Heart Rate ◽  
Relative Humidity ◽  
Environmental Factors ◽  
Thermal Comfort ◽  
Smart Home ◽  
Comfort Level ◽  
Human Model ◽  
Human Thermal Comfort ◽  
Air Speed ◽  
Individual Human

An environmental thermal comfort model has previously been quantified based on the predicted mean vote (PMV) and the physical sensors parameters, such as temperature, relative humidity, and air speed in the indoor environment. However, first, the relationship between environmental factors and physiology parameters of the model is not well investigated in the smart home domain. Second, the model that is not mainly for an individual human model leads to the failure of the thermal comfort system to fulfill the human’s comfort preference. In this paper, a cyber–physical human centric system (CPHCS) framework is proposed to take advantage of individual human thermal comfort to improve the human’s thermal comfort level while optimizing the energy consumption at the same time. Besides that, the physiology parameter from the heart rate is well-studied, and its correlation with the environmental factors, i.e., PMV, air speed, temperature, and relative humidity are deeply investigated to reveal the human thermal comfort level of the existing energy efficient thermal comfort control (EETCC) system in the smart home environment. Experimental results reveal that there is a tight correlation between the environmental factors and the physiology parameter (i.e., heart rate) in the aspect of system operational and human perception. Furthermore, this paper also concludes that the current EETCC system is unable to provide the precise need for thermal comfort to the human’s preference.

scholarly journals Evaporative Cooling Options for Building Air-Conditioning: A Comprehensive Study for Climatic Conditions of Multan (Pakistan)

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3061 ◽  
Author(s):  
Shazia Noor ◽  
Hadeed Ashraf ◽  
Muhammad Sultan ◽  
Zahid Mahmood Khan
Keyword(s):  
Thermal Comfort ◽  
Co2 Emissions ◽  
Air Conditioning ◽  
Evaporative Cooling ◽  
Cooling Capacity ◽  
Climatic Conditions ◽  
Maximum Temperature ◽  
Human Thermal Comfort ◽  
Work Input ◽  
System Configurations

This study provides comprehensive details of evaporative cooling options for building air-conditioning (AC) in Multan (Pakistan). Standalone evaporative cooling and standalone vapor compression AC (VCAC) systems are commonly used in Pakistan. Therefore, seven AC system configurations comprising of direct evaporative cooling (DEC), indirect evaporative cooling (IEC), VCAC, and their possible combinations, are explored for the climatic conditions of Multan. The study aims to explore the optimum AC system configuration for the building AC from the viewpoints of cooling capacity, system performance, energy consumption, and CO2 emissions. A simulation model was designed in DesignBuilder and simulated using EnergyPlus in order to optimize the applicability of the proposed systems. The standalone VCAC and hybrid IEC-VCAC & IEC-DEC-VCAC system configurations could achieve the desired human thermal comfort. The standalone DEC resulted in a maximum COP of 4.5, whereas, it was 2.1 in case of the hybrid IEC-DEC-VCAC system. The hybrid IEC-DEC-VCAC system achieved maximum temperature gradient (21 °C) and relatively less CO2 emissions as compared to standalone VCAC. In addition, it provided maximum cooling capacity (184 kW for work input of 100 kW), which is 85% higher than the standalone DEC system. Furthermore, it achieved neutral to slightly cool human thermal comfort i.e., 0 to −1 predicted mean vote and 30% of predicted percentage dissatisfied. Thus, the study concludes the hybrid IEC-DEC-VCAC as an optimum configuration for building AC in Multan.

Design Range of Indoor Relative Humidity in Radiant Cooling Environment

2011 ◽  
Vol 243-249 ◽  
pp. 4905-4908
Author(s):  
Xue Min Sui ◽  
Xu Zhang ◽  
Guang Hui Han
Keyword(s):  
Relative Humidity ◽  
Thermal Comfort ◽  
Mean Radiant Temperature ◽  
Design Standards ◽  
Human Thermal Comfort ◽  
Radiant Cooling ◽  
Climate Parameter ◽  
Radiant Temperature ◽  
Thermal Comfort Model ◽  
The Impact

Relative humidity is an important micro-climate parameter in radiant cooling environment. Based on the human thermal comfort model, this paper studied the effect on PMV index of relative humidity, and studied the relationship of low mean radiant temperature and relative humidity, drew the appropriate design range of indoor relative humidity for radiant cooling systems.The results show that high relative humidity can compensate for the impact on thermal comfort of low mean radiant temperature, on the premise of achieving the same thermal comfort requirements. However, because of the limited compensation range of relative humidity, together with the constraints for it due to anti-condensation of radiant terminal devices, the design range of relative humidity should not be improved, and it can still use the traditional air-conditioning design standards.

scholarly journals Human Thermal Comfort Situation in the Goller (Lakes) District of Turkey

2016 ◽  
pp. 137-144
Author(s):  
Yuksel Guclu
Keyword(s):  
Relative Humidity ◽  
Thermal Comfort ◽  
Human Health ◽  
Air Temperature ◽  
Mediterranean Region ◽  
Human Thermal Comfort ◽  
Almost All ◽  
Relative Humidity Data ◽  
Recreation Activities

Abstract In this study, the determination of the human thermal comfort situation in the Goller District (in the Mediterranean Region) of Turkey has been aimed. In the direction of the aim, the air temperature and relative humidity data of total 11 meteorology stations have been examined according to The Thermo-hygrometric Index (THI) and the New Summer Simmer Index (SSI). According to this, it has been determined that the thermal comfort conditions are not appropriate in the period of October-May on average monthly. The months of June and September are the most appropriate to almost all kinds of tourism and recreation activities in the outdoor in terms of thermal comfort. When THI and SSI indices’ values are evaluated together, the periods between 5th – 25th June and 29th August-16th September are the most appropriate periods in the study area on average in terms of the thermal comfort for the tourism and recreation activities in the outdoor. Keywords: Thermal comfort, human health, The Thermo-Hygrometric Index, The Summer Simmer Index, Goller District, Turkey.

A dynamic model for human thermal comfort for smart building applications

2019 ◽  
Vol 234 (4) ◽  
pp. 472-483
Author(s):  
Ghezlane Halhoul Merabet ◽  
Mohamed Essaaidi ◽  
Driss Benhaddou
Keyword(s):  
Thermal Comfort ◽  
Air Conditioning ◽  
Research Work ◽  
Comfort Level ◽  
Indoor Environments ◽  
Air Conditioning System ◽  
Human Thermal Comfort ◽  
Local Quality ◽  
Set Up ◽  
Air Conditioning Systems

Thermal comfort is closely related to the evaluation of heating, ventilation, and air conditioning systems. It can be seen as the result of the perception of the occupants of a given environment, and it is the product of the interaction of a number of personal and environmental factors. Otherwise, comfort issues still do not play an important role in the daily operation of commercial buildings. However, in the workplace, local quality effects, in addition to the health, the productivity that has a significant impact on the performance of the activities. In this regard, researchers have conducted, for decades, investigations related to thermal comfort and indoor environments, which includes developing models and indices through experimentations to establish standards to evaluate comfort and factors and set-up parameters for heating, ventilation, and air conditioning systems. However, to our best knowledge, most of the research work reported in the literature deals only with parameters that are not dynamically tracked. This work aims to propose a prototype for comfort measuring through a wireless sensor network and then presenting a model for thermal comfort prediction. The developed model can be used to set up a heating, ventilation, and air conditioning system to meet the expected comfort level. In particular, the obtained results show that there is a strong correlation between users’ comfort and variables such as age, gender, and body mass index as a function of height and weight.

Test Analysis of Performance of the Direct Evaporative Cooling Air Conditioners

2013 ◽  
Vol 827 ◽  
pp. 298-301
Author(s):  
Jian Zhang
Keyword(s):  
Relative Humidity ◽  
Evaporative Cooling ◽  
Cooling Capacity ◽  
Cooling Efficiency ◽  
Air Conditioner ◽  
Test Analysis ◽  
Air Conditioners ◽  
Direct Evaporative Cooling ◽  
Cooling Air ◽  
Analysis Of Performance

The direct evaporative cooling conditioner experimental research is carried out in this paper. Analyze the influence of inlet air dry ball temperature and relative humidity to air conditioner cooling capacity and cooling efficiency, which has certain guiding significance to improve the direct evaporative cooling air conditioner performance.

Study on Effects of Compressor Inlet Air Cooling on GTCC System Performance Under Different Environmental Conditions

2020 ◽  
Author(s):  
Duan Liqiang ◽  
Guo Yaofei ◽  
Pan Pan ◽  
Li Yongxia
Keyword(s):  
Relative Humidity ◽  
Ambient Temperature ◽  
Gas Turbine ◽  
Output Power ◽  
Environmental Conditions ◽  
System Performance ◽  
Combined Cycle ◽  
Air Cooling ◽  
Compressor Inlet ◽  
Cooling Technology

Abstract The environmental conditions (air temperature and relative humidity) have a great impact on the power and efficiency of gas turbine combined cycle (GTCC) system. Using the intake air cooling technology can greatly improve the performance of GTCC system. On the base of the PG9351FA gas turbine combined cycle system, this article builds the models of both the GTCC system and a typical lithium bromide absorption refrigeration system using Aspen Plus software. The effects of compressor inlet air cooling with different environmental conditions on the GTCC system performance are studied. The research results show that using the inlet air cooling technology can obviously increase the output powers of both the gas turbine and the combined cycle power. When the ambient humidity is low, the efficiency of GTCC changes gently; while the ambient humidity is high, the GTCC system efficiency will decline substantially when water in the air is condensed and removed with the progress of cooling process. At the same ambient temperature, when the relative humidity of the environment is equal to 20%, the gas turbine output power is increased by 35.64 MW, with an increase of 16.32%, and the combined cycle output power is increased by 39.57 MW, with an increase of 11.34%. At an ambient temperature of 35°C, for every 2.5 °C drop in the compressor inlet air, the thermal efficiency of the gas turbine increases by 0.189% compared to before cooling.

scholarly journals User Thermal Comfort in Historic Buildings: Evaluation of the Potential of Thermal Mass, Orientation, Evaporative Cooling and Ventilation

2020 ◽  
Vol 12 (22) ◽  
pp. 9672
Author(s):  
Mamdooh Alwetaishi ◽  
Ashraf Balabel ◽  
Ahmed Abdelhafiz ◽  
Usama Issa ◽  
Ibrahim Sharaky ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
High Altitude ◽  
Air Temperature ◽  
Thermal Performance ◽  
Indoor Air ◽  
Computer Modelling ◽  
Evaporative Cooling ◽  
Comfort Level ◽  
Thermal Mass ◽  
The Impact

The study investigated the level of thermal comfort in historical buildings located at a relatively high altitude in the Arabian Desert of Saudi Arabia. The study focused on the impact of the use of thermal mass and orientation on the level of thermal performance at Shubra and Boqri Palaces. Qualitative and quantitative analyses were used in this study, including a questionnaire interview with architecture experts living at the relatively high altitude of Taif city, to obtain data and information from local experts. The computer software TAS EDSL was used along with on-site equipment, such as thermal imaging cameras and data loggers, to observe the physical conditions of the building in terms of its thermal performance. The study revealed that the experts’ age and years of experience were important aspects while collecting data from them during the survey. The use of thermal mass had a slight impact on the indoor air temperature as well as the energy consumption, but it helped in providing thermal comfort. Use of ventilation can improve thermal comfort level. Evaporative cooling technique has a considerable impact on reducing indoor air temperature with 4 °C drop, improving the thermal comfort sensation level. The novelty of this work is that, it links the outcomes of qualitative results of experts with field monitoring as well as computer modelling. This can contribute as method to accurately collect data in similar case studies.

scholarly journals A MATHEMATICAL MODEL FOR DIRECT EVAPORATIVE COOLING AIR CONDITIONING SYSTEM

2003 ◽  
Vol 2 (2) ◽  
Author(s):  
J. R. Camargo ◽  
C. D. Ebinuma ◽  
S. Cardoso
Keyword(s):  
Mathematical Model ◽  
Air Conditioning ◽  
Cooling System ◽  
Convective Heat Transfer Coefficient ◽  
Evaporative Cooling ◽  
Experimental Tests ◽  
Water Evaporation ◽  
Human Thermal Comfort ◽  
Direct Evaporative Cooling ◽  
Evaporative Cooling System

Air conditioning systems are responsible for increasing men's work efficiency as well for his comfort, mainly in the warm periods of the year. Currently, the most used system is the mechanical vapor compression system. However, in many cases, evaporative cooling system can be an economical alternative to replace the conventional system, under several conditions, or as a pre-cooler in the conventional systems. It leads to a reduction in the operational cost, comparing with systems using only mechanical refrigeration. Evaporative cooling operates using induced processes of heat and mass transfer, where water and air are the working fluids. It consists in water evaporation, induced by the passage of an air flow, thus decreasing the air temperature. This paper presents the basic principles of the evaporative cooling process for human thermal comfort, the principles of operation for the direct evaporative cooling system and the mathematical development of the equations of thermal exchanges, allowing the determination of the effectiveness of saturation. It also presents some results of experimental tests in a direct evaporative cooler that take place in the Air Conditioning Laboratory at the University of Taubaté Mechanical Engineering Department, and the experimental results are used to determinate the convective heat transfer coefficient and to compare with the mathematical model.

Thermal comfort analysis of radiant cooling panels with dedicated fresh-air system

2020 ◽  
pp. 1420326X2096114
Author(s):  
S. Y. Qin ◽  
X. Cui ◽  
C. Yang ◽  
L. W. Jin
Keyword(s):  
Relative Humidity ◽  
Surface Temperature ◽  
Thermal Comfort ◽  
Air Temperature ◽  
Indoor Air ◽  
Area Ratio ◽  
Human Thermal Comfort ◽  
Air Supply ◽  
Radiant Cooling ◽  
Air System

Radiant system has been increasingly applied in buildings due to its good thermal comfort and energy-saving potential. In this research, a simplified predicted mean vote (PMV) model and sensible cooling load equation were proposed based on human thermal comfort. Simulations were carried out using Airpak to explore relationships among thermal comfort characteristics, design and operation parameters. Results show that radiant surface temperature, fresh-air supply temperature and the area ratio are correlated approximately linearly with the indoor air temperature, while the relative humidity has little effect on the indoor air temperature. The indoor air velocity in the simulated environment was no more than 0.15 m/s, satisfying the requirements of limit values in the occupied zone. The results indicate that the optimum radiant surface temperature ( tc) is 19°C to 23°C when fresh-air supply temperature ( ts) is 26°C. The relative humidity ( φ) should be maintained at 50% to 70%, and the area ratio of radiant panels to total surfaces ( k1) should be kept within 0.15 to 0.38 when the radiant surface temperature is 20°C and the fresh-air supply temperature is 26°C. The simplified PMV model and the sensible load equation can provide reference for panel design based on characteristics of radiant cooling panels with a dedicated fresh-air system.

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