Comparative Analysis of Vapor Compression and Hybrid Liquid Desiccant Dehumidification Systems

2005 ◽  
Author(s):  
A. M. Al-Jaafari ◽  
S. A. Sherif
Keyword(s):  
Energy Savings ◽  
Cooling System ◽  
The United States ◽  
Normal Operation ◽  
Weather Data ◽  
Energy Calculation ◽  
Vapor Compression ◽  
Liquid Desiccant ◽  
Study Results ◽  
Vapor Compression System

The objective of this study was to evaluate the energy savings of a commercially available hybrid liquid desiccant (HLD) cooling system relative to a conventional vapor compression system used for an existing school building where 100% outside air is used for ventilation. Psychrometric analysis and hour-by-hour simulations for three energy models were developed for three cities in the United States using available weather data assuming normal operation and typical building occupancy. Energy calculation software such as the Carrier Hourly Analysis Program (HAP 4.1) and Desicalc along with generated spreadsheets was used to compute the energy consumption for the models under study. Results of each model are summarized and comparisons are made. The annual energy savings employing the HLD system were found to reach 46% for Chicago, 37% for Gainesville and 32% for Miami. Simple cost analysis and associated payback periods were also performed.

The Development of a Model for a Solar-Fired, Single-Effect, Absorption Chiller

2008 ◽  
Author(s):  
Kevin E. Hinderliter ◽  
Isaac Y. Mahderekal ◽  
Robert F. Boehm
Keyword(s):  
Cooling System ◽  
Development Project ◽  
Weather Data ◽  
Thermal System ◽  
Vapor Compression ◽  
Specific System ◽  
Air Conditioning System ◽  
Vapor Compression System ◽  
Single Effect ◽  
Typical Summer

This study presents the concept, functionality, and economics of a solar-fired, single-effect, absorption air conditioning system. The goal of this project was to develop a mathematical model to determine efficiencies and capacities, which are then compared with a traditional 28 kW (8 ton) packaged vapor compression system. This comparison is then used to determine economic conclusions. The thermal system being examined is part of a proposed research and development project located in Phoenix, Arizona. This specific system will contain a six-module, single-axis, concentrating solar collector, a 119 gallon (450 L) storage tank, and a 35kW chiller. Using MatLab with Typical Meteorological Year 2 (TMY2) weather data [1], a model was created from readily available manufacturer specifications. After completing the model it was determined that the annual savings can range from $3,448 to $1,737 with simple payback periods of 18 to 36 years depending on collector efficiencies and current electrical rates. The model also proved that the proposed cooling system can supply over 20 kW of continuous cooling for 8 hours on a typical summer day.

Optimized Refrigerant Flow Rate and Dimensions of the Ejector Employed in a Modified Ejector Vapor Compression System

2020 ◽  
Vol 28 (04) ◽  
pp. 2050038
Author(s):  
Dishant Sharma ◽  
Gulshan Sachdeva ◽  
Dinesh Kumar Saini
Keyword(s):  
Flow Rate ◽  
Cooling System ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Evaporator Temperature ◽  
Proposed Model ◽  
Condenser Temperature ◽  
Vapor Compression System ◽  
Vapor Compression Cooling

This paper presents the analysis of a modified vapor compression cooling system which uses an ejector as an expansion device. Expanding refrigerant in an ejector enhances the refrigeration effect and reduces compressor work. Therefore, it yields a better coefficient of performance. Thermodynamic analysis of a constant area ejector model has been done to obtain primary dimensions of the ejector for given condenser and evaporator temperature and cooling capacity. The proposed model has been used to design the ejector for three refrigerants; R134a, R152a and R1234yf. The refrigerant flow rate and the diameters at various sections of the ejector have been obtained by doing numerical modeling in Engineering Equation Solver (EES). Refrigerant R1234yf demanded the highest diameter requirements at a fixed 5∘C evaporator temperature and 40∘C condenser temperature for a given range of cooling load. Both primary and secondary refrigerants flow rates are higher for R1234yf followed by R134a and then R152a.

A New Approach to Exergy Analyses of a Hybrid Desiccant Cooling System Compares to a Vapor Compression System

2011 ◽  
Vol 110-116 ◽  
pp. 2163-2169
Author(s):  
S. Khosravi ◽  
Yat Huang Yau ◽  
T.M.I. Mahlia ◽  
M.H. Saidi
Keyword(s):  
Indoor Air ◽  
Cooling System ◽  
Vapor Compression ◽  
Cooling Systems ◽  
New Approach ◽  
Compression System ◽  
Humid Condition ◽  
Economical System ◽  
Vapor Compression System ◽  
Exergy Analyses

In the recent researches HVAC with a based desiccant dehumidifier with a low ambient impact is more efficient in comparison to the traditional systems. Hybrid desiccant cooling systems can be used to control indoor air quality in buildings. This paper presents an integrated energy, entropy and exergy analysis of a hybrid desiccant cooling system compare to a compression system based on first and second laws of thermodynamic. The main objective is the use of a method called exergy costing applied to a conventional compression system that has been chosen to provide the proper conditioned air for a building in hot and humid condition. By applying the same method for the equivalent hybrid cooling system and finding the same exergy costing parameters, two systems can be in comparison to find the more economical system. The result illustrated hybrid desiccant cooling system can be providing 19.78% energy saving and 14.5% cheaper than the compression system the same capacity and lifetime. Nomenclature:

scholarly journals Next-Generation HVAC: Prospects for and Limitations of Desiccant and Membrane-Based Dehumidification and Cooling

2017 ◽  
Author(s):  
Omar Labban
Keyword(s):  
Cooling System ◽  
System Level ◽  
Device Performance ◽  
Vapor Compression ◽  
Next Generation ◽  
Outdoor Temperature ◽  
Cooling Process ◽  
Vapor Compression System ◽  
Shed Light ◽  
Specific Technology

Recently, next-generation HVAC technologies have gained attention as potential alternatives to the conventional vapor-compression system (VCS) for dehumidification and cooling. Previous studies have primarily focused on analyzing a specific technology or its application to a particular climate. A comparison of these technologies is necessary to elucidate the reasons and conditions under which one technology might outperform the rest. In this study, we apply a uniform framework based on fundamental thermodynamic principles to assess and compare different HVAC technologies from an energy conversion standpoint. The thermodynamic least work of dehumidification and cooling is formally defined as a thermodynamic benchmark, while VCS performance is chosen as the industry benchmark against which other technologies, namely desiccant-based cooling system (DCS) and membrane-based cooling system (MCS), are compared. The effect of outdoor temperature and humidity on device performance is investigated, and key insights underlying the dehumidification and cooling process are elucidated. In spite of the great potential of DCS and MCS technologies, our results underscore the need for improved system-level design and integration if DCS or MCS are to compete with VCS. Our findings have significant implications for the design and operation of next-generation HVAC technologies and shed light on potential avenues to achieve higher efficiencies in dehumidification and cooling applications.

Refrigeration Heat Exchanger Systems for Server Rack Cooling in Data Centers

2009 ◽  
Author(s):  
Takeshi Tsukamoto ◽  
Jyunji Takayoshi ◽  
Roger R. Schmidt ◽  
Madhusudan K. Iyengar
Keyword(s):  
Heat Exchanger ◽  
Data Center ◽  
Heat Exchangers ◽  
Energy Savings ◽  
Vapor Compression ◽  
Data Center Cooling ◽  
Thermal Data ◽  
Coolant Loop ◽  
Vapor Compression System

In 2005, IBM released a water cooled heat exchanger product that significantly enhanced data center cooling capability while also demonstrating substantial energy savings. In 2008, IBM released an enhanced water less solution to cool the electronic racks via a R410A refrigerant based vapor compression system, which is the focus of this paper. The paper provides a detailed description of device and coolant loop construction, the experimental thermal data collected, as well as a discussion of its’ cooling energy efficiency relative to both typical air cooled facilities and water cooled heat exchangers, respectively. A data center level case study was performed with experimental measurements collected and discussed herein. Significant energy savings were realized even when the heat exchanger devices were implemented on a small part of the data center. Based on the test data and the experimental data center study, the CRAC units based loops have a COP of 1.95, while the refrigerant refrigerant heat exchanger loop has a COP of 5.0.

scholarly journals Analysis of supplemental dehumidification for increased energy efficiency of shoulder seasons based on climate change predictions in Austin Texas

2021 ◽  
Vol 2042 (1) ◽  
pp. 012182
Author(s):  
B Marshall ◽  
J Felkner ◽  
Z Nagy
Keyword(s):  
Climate Change ◽  
Energy Efficiency ◽  
Potential Energy ◽  
Energy Efficient ◽  
Air Conditioning ◽  
Energy Savings ◽  
Vapor Compression ◽  
Compression System ◽  
Vapor Compression System ◽  
American Society

Abstract This research project compared a standard vapor compression system and a standard desiccant dehumidification system with heat wheel to determine if there was some potential energy savings for “shoulder season” hours in Austin Texas. “Shoulder season” hours as defined in the paper are hours during which the dry bulb temperature falls within the American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) comfort bound but the humidity is above the comfortable humidity point. These hours are normally addressed with vapor compression systems which dehumidify by cooling the air under the comfort setpoint to dehumidify, which is wasteful of energy. The study found that for these shoulder season hours a desiccant dehumidification system was around 4.5 times more energy efficient at reaching comfort setpoints if free heating was used for drying the desiccant.

A Study of the Performance of a Hybrid Liquid Desiccant Cooling System Using Lithium Chloride

2003 ◽  
Vol 125 (1) ◽  
pp. 129-131 ◽  
Author(s):  
Pedro Mago ◽  
D. Yogi Goswami
Keyword(s):  
Mass Flow Rate ◽  
Field Test ◽  
Mass Flow ◽  
Flow Rate ◽  
Air Conditioning ◽  
Cooling System ◽  
Liquid Desiccant ◽  
Test House ◽  
Vapor Compression System ◽  
Research And Education

This paper presents field test of a hybrid solar liquid desiccant cooling system conducted at a test house at the University of Florida’s Energy Research and Education Park. These tests consisted of operating the air conditioning system at the test house in two configurations: the conventional vapor compression system and the hybrid desiccant system. Experiments were conducted to study the influence of the air mass flow rate, temperature of the inlet air, temperature of the desiccant, and desiccant mass flow rate on the performance of both system configurations. Based on the field test results, it was found that the hybrid desiccant system improves the air conditioning performance in the field test house by decreasing the outlet humidity and temperature of the air.

Experimental and simulation study of the performance of a desiccant loop cooling system

2021 ◽  
pp. 095765092110105
Author(s):  
R Venkatesh ◽  
Madhu Ganesh ◽  
S Suriyaprakash ◽  
SE Deva Surya ◽  
L Ashok Kumar ◽  
...  
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Cooling System ◽  
Vapor Compression ◽  
Ambient Conditions ◽  
Experimental Conditions ◽  
Vapor Compression System ◽  
Reduced Power Consumption ◽  
Indian Cities

The paper presents experimental data and results from a prediction tool for the performance of a desiccant loop cooling system. The experiments are performed under a variety of high humidity and hot ambient conditions and the system performance is described. One of the experimental conditions is typical of many Indian cities and the systems appropriate for those cities are established. A simulation program that can predict the performance of the desiccant loop is developed. The simulation results show that this system can work as effectively as vapor compression air-conditioning for certain ambient conditions whereas it can function as a pre-cooler to a vapor compression system under more severe conditions, resulting in a reduced power consumption. The results presented in the paper give a guideline to practicing engineers as to when a desiccant loop cooling system would be useful. A simple payback analysis and a lifecycle cost analysis shows that a desiccant cooling system with a waste heat recovery recuperator is an economically viable investment.

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