scholarly journals Improving performance of direct expansion air conditioning systems while reducing electricity consumption through using hybrid energy

2021 ◽  
Vol 289 ◽  
pp. 01014
Author(s):  
Ahmed Al–Okbi ◽  
Yuri Vankov ◽  
Hakim Kadhim
Keyword(s):  
Energy Consumption ◽  
Thermal Energy ◽  
Air Conditioning ◽  
Electrical Energy ◽  
Coefficient Of Performance ◽  
Electricity Production ◽  
Conventional System ◽  
Solar Thermal Energy ◽  
Continuous Power ◽  
Air Conditioning Systems

At the present time, operating hybrid air-conditioning systems that use solar energy to saving electrical energy while improving the performance has become necessary to protect the environment, reduce pollution and emissions caused by using fuels and gases. In Iraq, temperatures reach half the boiling point at summer, therefore the demand for air conditioning systems increases, air conditioning systems consume more than half of average electricity production which affects on reliability and stability of the electrical energy thus leads to a continuous power outage. So, the issue of using renewable energies becomes more attractive. Because of saving energy leads to ensuring the reliability of electricity and reduces the consumption of fuels and gases that pollute on the environment and negatively affect on the ozone layer. In the current research, the atmosphere of Baghdad city was used to collect solar thermal energy and convert it into thermal energy through an evacuated solar collector by water and combine it with a conventional air conditioner in the part that follows the compressor in order to reduce the electrical energy consumption on the compressor and increase coefficient of performance. Several tests were conducted on the proposed system to compare results with the conventional system and evaluate performance. The results showed that the coefficient of performance with the hybrid system became 8.97 more efficient instead of 4.27 compared to the conventional system, and the energy consumption decreased by 52%.

scholarly journals A hybrid air conditioning system using solar energy to save electrical energy with improving performance

2021 ◽  
Vol 288 ◽  
pp. 01066
Author(s):  
Ahmed Al–Okbi ◽  
Yuri Vankov ◽  
Hasanen Mohammad Hussain
Keyword(s):  
Energy Consumption ◽  
Solar Energy ◽  
Solar Collector ◽  
Air Conditioning ◽  
Electrical Energy ◽  
Coefficient Of Performance ◽  
Electricity Production ◽  
Air Conditioner ◽  
Solar Thermal Energy ◽  
Air Conditioning System

The process of operating an air conditioning system by hybrid energy that uses solar energy for purpose of saving electrical energy with improving the performance from modern and environmentally friendly systems. With high demand for air-conditioning systems in summer in hot regions, especially in Iraq due to high temperatures, the issue of using renewable energies becomes more attractive due to the continuous interruption of electrical energy. Air conditioners in Iraq consume more than half of the average electricity production. Therefore, saving energy leads to ensuring the reliability of electricity and reduces the consumption of fuel and gases that pollute the environment and negatively affect on the ozone layer. In the current research, the atmosphere of the city Baghdad was used to collect the solar thermal energy through a vacuum solar collector and combine it with a conventional air conditioner in order to reduce the electrical energy consumption on the compressor and increase the coefficient of performance. Several tests were conducted on the experimental device for comparing results with the conventional device and evaluating performance. The results showed that the performance with the vacuum solar collector became more efficient 8.97 instead of 4.27 than with the conventional system, and the energy consumption decreased by 52%.

Use of Solar Desiccant Air-Conditioning Systems in Commercial Buildings

Solar Energy ◽  
2005 ◽  
Author(s):  
Anthony Domenic Calderone ◽  
Mir-Akbar Hessami ◽  
Stefan Brey
Keyword(s):  
Air Conditioning ◽  
Greenhouse Gas Emission ◽  
Electrical Energy ◽  
Sole Source ◽  
Solar Thermal ◽  
Commercial Building ◽  
Solar Thermal Energy ◽  
Cooling Cycle ◽  
Solar Thermal Collectors ◽  
Air Conditioning Systems

Desiccant air conditioning systems provide an environmentally friendly alternative to the traditional methods of conditioning a building’s internal environment. Whilst conventional air conditioning systems rely on electrical energy to drive the cooling cycle, desiccant cooling is a heat driven cycle. As such, desiccant cooling provides an opportunity to be coupled with solar thermal collectors to reduce energy demands. This paper discusses the potential for a desiccant cooling cycle utilising solar thermal energy as the sole source of heat for regeneration of the desiccant. The study demonstrates that under the assumed design conditions this system will theoretically not require a regeneration heater. Installation of such a system in a commercial building would be extremely beneficial in reducing building’s energy consumption and therefore greenhouse gas emission.

Comparison study of air mixing modes in liquid desiccant based all-air air conditioning systems

2011 ◽  
Vol 33 (4) ◽  
pp. 423-435 ◽  
Author(s):  
Fu Xiao ◽  
XiaoFeng Niu
Keyword(s):  
Energy Consumption ◽  
Air Conditioning ◽  
Coefficient Of Performance ◽  
Liquid Desiccant ◽  
Total Energy Consumption ◽  
Air Conditioning System ◽  
Operation Conditions ◽  
Air System ◽  
Air Mixing ◽  
Air Conditioning Systems

Liquid desiccant is an energy-saving, environmentally friendly and healthy means of air dehumidification. A liquid desiccant-based all-air air conditioning system is studied by simulation. Two different modes of air mixing between the return air and the fresh air are compared, that is mixing before and mixing after the liquid desiccant dehumidifier, respectively. System performance and total energy consumption of the two modes under different operation conditions are obtained. The results show that mixing air after dehumidification consumes less energy than mixing air before dehumidification. Coefficient of performance (COP) of the all-air system with air mixing after dehumidification is higher. The differences of COP and energy consumption between the two air mixing modes increase when the outdoor air temperature and relative humidity increase. Practical application: Liquid desiccant based all-air system is quite suitable for museums, libraries and computer centres where water is not allowed to enter the space for property safety and strict thermal-hygrometric control is necessary. The results of this paper provide guidelines on the selection of air mixing modes in liquid desiccant-based all-air systems, considering energy consumption and system COP.

Experimental Study on a Hybrid Desiccant Dehumidification and Air Conditioning System

2005 ◽  
Vol 128 (1) ◽  
pp. 77-82 ◽  
Author(s):  
Li Yong ◽  
K. Sumathy ◽  
Y. J. Dai ◽  
J. H. Zhong ◽  
R. Z. Wang
Keyword(s):  
Air Conditioning ◽  
Experimental Tests ◽  
Electrical Energy ◽  
Primary Energy ◽  
Coefficient Of Performance ◽  
Air Flow Rate ◽  
Energy Usage ◽  
Humidity Ratio ◽  
Air Conditioning System ◽  
Air Conditioning Systems

This paper presents the experimental tests on hybrid desiccant dehumidification and air conditioning systems. Experimental tests are carried out with LiCl desiccant at typical operative ranges for air conditioning applications, particularly for high humid regions like Hong Kong. Results are reported in terms of coefficient of performance (COP) based on primary energy usage and electrical energy usage, respectively. Experiments have demonstrated consistent reduction in humidity ratio satisfying the sensible as well as latent load through a respective subsystem and thereby resulting in a higher COP based on primary energy usage. Also, results show that the regeneration temperature as well as process air flow rate have a significant role on the system performance. It is found that the hybrid system can achieve a higher part load performance, and hence can assure of its effective operation all year around in hot humid regions.

APPLICATION OF HYDROCARBON BASED REFRIGERANTS FOR AIR CONDITIONING IN INDONESIA

2011 ◽  
Vol 19 (04) ◽  
pp. 303-309 ◽  
Author(s):  
ARI D. PASEK ◽  
ARYADI SUWONO
Keyword(s):  
Global Warming ◽  
Energy Consumption ◽  
Air Conditioning ◽  
Performance Test ◽  
Saturation Pressure ◽  
Electrical Energy ◽  
Electrical Energy Consumption ◽  
Refrigerant Mixture ◽  
R 134A ◽  
Air Conditioning Systems

Electrical energy consumption in air conditioning systems reaches 60% to 70% of the total electric energy consumption in buildings. Therefore, saving electrical energy consumption in air conditioning systems would have a significant impact on the national electrical energy consumption. Currently, the air conditioning sectors were having a dilemma on finding the alternative substitutes for CFC and HCFC refrigerants which are proven to cause destruction of the ozone layer and contribute to the effects of global warming. This paper will discuss the problems faced by an Article 5 country similar to Indonesia in phasing-out HCFC especially in air conditioning and refrigeration sectors. This paper will also discuss the possibility to use hydrocarbon-based refrigerants, which have zero ozone depletion potential (ODP) and low global warming potential (GWP), in air conditioning sectors. Some results of field applications of this refrigerant will be reported, and in general it can be concluded that the air conditioning retrofitted with hydrocarbon refrigerant consumes 10%–20% less electrical energy. Mixture of R-290 and R-134a was also investigated. R-134a is used to reduce the flammability of R-290 and to make the saturation pressure close to R-22. The results show that at composition of 0.6 R-290/0.4 R-134a mole fractions, the mixture behave as an azeotrope refrigerant mixture and can be used for R-22 replacement. At this composition, lower flammability limit (LEL) is 3693%, which is higher than pure R-290. Hence, the refrigerant mixture can be classified as less flammable A2 class refrigerant. The performance test shows that the refrigerant mixture can be used as a drop-in refrigerant in the R-22 machine. The measurement of refrigeration capacity and compressor input work at the same chilled water temperature shows that the calculated COP of the refrigerant mixture is better than R-22's but lower than R-290's.

Energy and Cost Minimal Control of Active and Passive Building Thermal Storage Inventory

2005 ◽  
Vol 127 (3) ◽  
pp. 343-351 ◽  
Author(s):  
Gregor P. Henze
Keyword(s):  
Optimal Control ◽  
Energy Consumption ◽  
Thermal Energy ◽  
Peak Load ◽  
Cost Savings ◽  
Electrical Energy ◽  
Thermal Storage ◽  
Coefficient Of Performance ◽  
Electrical Energy Consumption ◽  
Electricity Cost

In contrast to building energy conversion equipment, less improvement has been achieved in thermal energy distribution, storage and control systems in terms of energy efficiency and peak load reduction potential. Cooling of commercial buildings contributes significantly to the peak demand placed on an electrical utility grid and time-of-use electricity rates are designed to encourage shifting of electrical loads to off-peak periods at night and on weekends. Buildings can respond to these pricing signals by shifting cooling-related thermal loads either by precooling the building’s massive structure (passive storage) or by using active thermal energy storage systems such as ice storage. Recent theoretical and experimental work showed that the simultaneous utilization of active and passive building thermal storage inventory can save significant amounts of utility costs to the building operator, yet increased electrical energy consumption may result. The article investigates the relationship between cost savings and energy consumption associated with conventional control, minimal cost and minimal energy control, while accounting for variations in fan power consumption, chiller capacity, chiller coefficient-of-performance, and part-load performance. The model-based predictive building controller is employed to either minimize electricity cost including a target demand charge or electrical energy consumption. This work shows that buildings can be operated in a demand-responsive fashion to substantially reduce utility costs with marginal increases in overall energy consumption. In the case of energy optimal control, the reference control was replicated, i.e., if only energy consumption is of concern, neither active nor passive building thermal storage should be utilized. On the other hand, cost optimal control suggests strongly utilizing both thermal storage inventories.

Retrofitting R-22 Split Type Air Conditioning with Hydrocarbon (HCR-22) Refrigerant

2013 ◽  
Vol 388 ◽  
pp. 91-95 ◽  
Author(s):  
Henry Nasution ◽  
Abdul Latiff Zulkarnain ◽  
Azhar Abdul Aziz ◽  
Mohd Rozi Mohd Perang
Keyword(s):  
Energy Consumption ◽  
Air Conditioning ◽  
Room Temperature ◽  
Internal Heat ◽  
Electrical Energy ◽  
Coefficient Of Performance ◽  
Cooling Load ◽  
Refrigeration System ◽  
Electrical Energy Consumption ◽  
The One

An experimental study to evaluate the energy consumption of a split type air conditioning is presented. The compressor works with the fluids R-22 and HCR-22 and has been tested varying the internal heat load 0, 500, 700 and 1000 W. The measurements taken during the one hour experimental periods at 10-minutes interval times for temperature setpoint of 20oC. The performance data considered where the evaporator cooling load, the condenser heat rejection, the electrical energy consumption, the refrigeration system temperatures, and the room temperature. And hence the Coefficient of Performance (COP) could be determined. The final results of this study show an overall better energy consumption of the HFC-22 compared with the R-22.

Hybrid Liquid Desiccant/Vapour Compression Air-Conditioning Systems: A Critical Review

2008 ◽  
Author(s):  
Roza I. Christodoulaki ◽  
Emmanuil D. Rogdakis ◽  
Irene P. Koronaki
Keyword(s):  
Air Conditioning ◽  
Waste Heat ◽  
Electrical Energy ◽  
Hot Water ◽  
Vapor Compression ◽  
Solar Thermal Energy ◽  
Liquid Desiccant ◽  
Design Variables ◽  
Air Conditioning Systems ◽  
Vapour Compression

Hybrid Liquid Desiccant Cooling / Vapour Compression Systems is an environmentally friendly technology used to condition the internal environment of buildings. In contrast to conventional vapor compression air conditioning systems, in which the electrical energy drives the cooling cycle, desiccant cooling is heat driven; therefore, hybrid LDC/VCS have the potential to utilise cleaner energy sources such as gas, hot water, waste heat or solar thermal energy. In hybrid LDC/VCS, the latent cooling load is handled by the desiccant dehumidifier, while the sensible is handled by a conventional VCS. Hybrid systems combining liquid desiccant cooling with Vapor Compression Systems, Vapor Absorption Systems and Solar Collectors use less electrical energy compared to conventional air-conditioning alone, while these savings rise as the latent load increases. Unlike other surveys on desiccant cooling, this review focuses on a detailed coverage of the hybrid LDC/VC systems. Commonly used liquid desiccants are compared towards their physical properties. Hybrid LDC/VCS employing various components and features are summarized, while different system configurations are schematically presented. Key factors for the hybrid system performance are the desiccant material, the design variables and the conduction of experiments prior to operation.

scholarly journals Assessing the energy performance of VAV and VRF air conditioning systems in an office building located in the city of Florianópolis

2020 ◽  
Vol 20 (2) ◽  
pp. 261-283
Author(s):  
Vanessa Cavalcanti Paes Duarte ◽  
Ana Paula Melo ◽  
Roberto Lamberts
Keyword(s):  
Energy Consumption ◽  
Air Conditioning ◽  
Energy Use ◽  
Load Ratio ◽  
Energy Performance ◽  
Office Building ◽  
Coefficient Of Performance ◽  
Partial Load ◽  
Air Conditioning Systems ◽  
The City

Abstract The objective of this study is to analyze the energy performance of two types of water-cooled air conditioning systems, variable air volume (VAV) and variable refrigerant flow (VRF), in terms of their cooling energy use through building simulation. These systems were designed to operate in an office building located in the city of Florianópolis, Brazil. The analysis involved the application of two building use schedules: a) constant and b) variable. Moreover, an analysis of the coefficient of performance (COP) and partial load ratio (PLR), and the percentage of operating hours for each range of cooling COP and PLR for each air conditioning system, allowed the system cooling efficiency to be assessed and the results to be related to the annual energy consumption. The coefficient of performance of VAV and VRF is 6.7 and 5.0, respectively, but the VRF system presented the lowest energy consumption for both schedules. The difference in the cooling energy consumption values for the VRF and VAV systems, for the variable schedule compared with the constant schedule, is mainly influenced by the partial load performance during the hottest period of the year.

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