scholarly journals Energy Efficient Rooftop Air-Conditioner

2003 ◽  
Author(s):  
Detlef Westphalen ◽  
William Murphy
Keyword(s):  
Energy Efficient ◽  
Air Conditioner ◽  
Rooftop Air Conditioner

scholarly journals Performance and environmental effects of refrigerants used in the rooftop air-conditioning of building for carbon emission: A case of theoretical and numerical modelling

2021 ◽  
Author(s):  
Kaan Suerdem ◽  
Tolga Taner ◽  
Ozgen Acikgoz ◽  
Ahmet Selim Dalkilic ◽  
Somchai Wongwises
Keyword(s):  
Energy Consumption ◽  
Environmental Effects ◽  
Experimental Tests ◽  
Cooling Capacity ◽  
Simulation Program ◽  
Air Conditioner ◽  
Performance Review ◽  
Equal Energy ◽  
Different Characteristics ◽  
Rooftop Air Conditioner

Abstract This study analyzes six different refrigerants with different characteristics using the same rooftop air conditioner considering the environmental effects unlike other studies. All evaluations are drafted in two different scenarios, thanks to the equal refrigerant charge amount and equal energy consumption to make the performance review more accurate. Cooling capacity, energy consumption, temperature and pressure values are obtained through a numerical simulation program so as to obtain performance values. In order to prove the accuracy of the values obtained from the simulation program, the rooftop air conditioner using R410A refrigerant is tested in the laboratory environment. The Life Cycle Climate Performance method is used for environmental analyses to calculate the carbon emissions of six different refrigerants in two different scenarios. These experimental tests are carried out at outdoor temperatures of 20ºC, 25ºC, 30ºC and 35ºC. The maximum difference in cooling capacity, energy consumption and energy efficiency is determined as 2.8% between simulation and experimental outputs. According to the results from and equal refrigerant charged and equal energy consumption scenarios, R410A, R454B and R32 refrigerants are found to have better cooling capacities than other refrigerants in performance analyses.

scholarly journals A Zero Carryover Liquid-Desiccant Air Conditioner for Solar Applications

Solar Energy ◽  
2006 ◽  
Author(s):  
Andrew Lowenstein ◽  
Steve Slayzak ◽  
Eric Kozubal
Keyword(s):  
Indoor Air ◽  
Mass Exchange ◽  
Energy Efficient ◽  
Low Flow ◽  
Air Conditioner ◽  
Liquid Desiccant ◽  
Heat And Mass Exchange ◽  
Pressure Drops ◽  
Simultaneous Heat ◽  
Contact Liquid

A novel liquid-desiccant air conditioner that dries and cools building supply air has been successfully designed, built and tested. The new air conditioner will transform the use of direct-contact liquid-desiccant systems in HVAC applications, improving comfort and indoor air quality, as well as providing energy-efficient humidity control. Liquid-desiccant conditioners and regenerators are traditionally implemented as adiabatic beds of contact media that are highly flooded with desiccant. The possibility of droplet carryover into the supply air has limited the sale of these systems in most HVAC applications. The characteristic of the new conditioner and regenerator that distinguishes them from conventional ones is their very low flows of liquid desiccant. Whereas a conventional conditioner operates typically at between 10 and 15 gpm (630 and 946 ml/s) of desiccant per 1000 cfm (0.47 m3/s) of process air, the new conditioner operates at 0.5 gpm (32 ml/s) per 1000 cfm (0.47 m3/s). At these low flooding rates, the supply air will not entrain droplets of liquid desiccant. This brings performance and maintenance for the new liquid-desiccant technology in line with HVAC market expectations. Low flooding rates are practical only if the liquid desiccant is continually cooled in the conditioner or continually heated in the regenerator as the mass exchange of water occurs. This simultaneous heat and mass exchange is accomplished by using the walls of a parallel-plate plastic heat exchanger as the air/desiccant contact surface. Compared to existing solid and liquid desiccant systems, the low-flow technology is more compact, has significantly lower pressure drops and does not “dump” heat back onto the building’s central air conditioner. Tests confirm the high sensible and latent effectiveness of the conditioner, the high COP of the regenerator, and the operation of both components without carryover.

Life Cycle Analysis of Energy Efficient Measures in a Tropical Housing Design

2005 ◽  
Author(s):  
Michael G. Duell ◽  
Lorien A. Martin
Keyword(s):  
Life Cycle ◽  
Energy Efficient ◽  
Life Cycle Analysis ◽  
Embodied Energy ◽  
Thermal Mass ◽  
Air Conditioner ◽  
Efficient Design ◽  
Housing Design ◽  
Tropical Conditions ◽  
Efficient Measures

Energy conservation has become an issue of global significance, which is a focus reflected in the Australian housing industry’s renewed emphasis on energy-efficient design. The Australian Building Codes Board (ABCB) has proposed to increase the stringency of the Building Code of Australia (BCA) to ensure the industry adopts energy efficient measures, including the enhancement of thermal performance and greater recognition of thermal mass in energy rating schemes. However, this proposal’s potential to effect energy savings in tropical housing is yet to be assessed. In order to determine its relative merits under tropical conditions, a standardised house design used in the Tiwi Islands of the Northern Territory (NT) was subjected to life cycle analysis, including analysis of embodied energy, the efficiency of energy saving measures and the resulting active energy consumption. This standardised house, like others in the NT, is designed for retrofitting within 10 years, which reduces the time available for savings in operational energy to exceed energy invested in installing these measures. Housing lifespan would, therefore, significantly impact upon potential benefits resulting from changes to the BCA. In addition, the spatial distances between population settlements in the NT greatly increases embodied energy values. It was found that adopting the proposed measures would result in an increase in energy efficiency through a reduction in the need for refrigerative air conditioner use, and that the embodied energy payback period would fall within the lifespan of the house. Therefore, for this specific tropical design, the BCA’s proposed measures for saving energy were found to be beneficial.

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