Performance Evaluation of a 4.5 kW (1.3 Refrigeration Tons) Air-Cooled Lithium Bromide/Water Hot-Water-Fired Absorption Unit

2007 ◽  
Author(s):  
Abdolreza Zaltash ◽  
Andrei Petrov ◽  
Randall Linkous ◽  
Edward Vineyard ◽  
David Goodnack ◽  
...  
Keyword(s):  
Heat Exchangers ◽  
Air Conditioning ◽  
Cooling Tower ◽  
Lithium Bromide ◽  
Cooling Capacity ◽  
Hot Water ◽  
Next Generation ◽  
Absorption Chiller ◽  
Flow Rates ◽  
Absorption Chillers

During the summer months, air-conditioning (cooling) is the single largest use of electricity in both residential and commercial buildings with the major impact on peak electric demand. Improved air-conditioning technology has by far the greatest potential impact on the electric industry compared to any other technology that uses electricity. Thermally activated absorption air-conditioning (absorption chillers) can provide overall peak load reduction and electric grid relief for summer peak demand. This paper describes an innovative absorption technology based on integrated rotating heat exchangers to enhance heat and mass transfer resulting in a potential reduction of size, cost, and weight of the “next generation” absorption units. This absorption chiller (RAC) is a 4.5 kW (1.3 refrigeration tons or RT) air-cooled lithium bromide (LiBr)/water unit powered by hot water generated using the solar energy and/or waste heat. Typically LiBr/water absorption chillers are water-cooled units which use a cooling tower to reject heat. Cooling towers require a large amount of space and increase start-up and maintenance costs. However, RAC is an air-cooled absorption chiller which requires no cooling tower. The purpose of this evaluation is to verify RAC performance by comparing the Coefficient of Performance (COP or ratio of cooling capacity to thermal energy input) and the cooling capacity results with those of the manufacturer. The performance of the RAC was tested at Oak Ridge National Laboratory (ORNL) in a controlled environment at various hot and chilled water flow rates, air handler flow rates, and ambient temperatures. Temperature probes, mass flow meters, rotational speed measuring device, pressure transducers, and a web camera mounted inside the unit were used to monitor the RAC via a web control-based data acquisition system using Automated Logic Controller (ALC). Results showed a COP and cooling capacity of approximately 0.58 and 3.7 kW respectively at 35°C (95°F) design condition for ambient temperature with 40°C (104°F) cooling water temperature. This is in close agreement with the manufacturer data of 0.60 for COP and 3.9 kW for cooling capacity. Future work will use these performance results to evaluate the potential benefits of rotating heat exchangers in making the “next-generation” absorption chillers more compact and cost effective without any significant degradation in the performance. Future studies will also evaluate the feasibility of using rotating heat exchangers in other applications.

scholarly journals Conversion of gas engine waste heat into cold using absorption chillers

2020 ◽  
Vol 168 ◽  
pp. 00046
Author(s):  
Georgii Karman ◽  
Yurii Oksen ◽  
Olena Trofymova ◽  
Yurii Komissarov ◽  
Borys Dizhevskyi ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Waste Heat ◽  
Lithium Bromide ◽  
Thermodynamic Cycle ◽  
Cooling Capacity ◽  
Coolant Temperature ◽  
Gas Engine ◽  
Absorption Chillers ◽  
Full Conversion ◽  
Heating Medium

A possibility of gas engine waste heat conversion into cold for air conditioning in mines using lithium bromide absorption chillers is investigated. Dependencies of parameters of a thermodynamic cycle and energy indicators of chillers on temperatures of a heating medium and a coolant are obtained using mathematical modelling. It is shown that it is rational to use two chillers with sequential movement of a heating medium and a coolant through them in opposite directions for a full conversion of gas engine waste heat. COP of such a system is 0.733. This allows obtaining 2140 kW of cooling capacity with a coolant temperature of 7 °C when using a gas engine JMS-620 by Jenbacher.

Efficient Replacement of Centrifugal With Absorption Chillers Upgrading the Heat Transfer of the Cooling Tower

2001 ◽  
Author(s):  
E. D. Rogdakis ◽  
V. D. Papaefthimiou
Keyword(s):  
Flow Rate ◽  
Cooling Tower ◽  
Water Flow Rate ◽  
Cooling Water ◽  
Double Effect ◽  
Operating Conditions ◽  
Cooling Power ◽  
Absorption Chiller ◽  
Absorption Chillers ◽  
Cooling Water Flow Rate

Abstract It is a general trend today, the old centrifugal machines to be replaced by new absorption machines. The mass flow rate of the cooling water in the centrifugal machines is normally 30% less than that in the two-stage absorption chiller for the same refrigerating capacity. Some absorption chillers manufacturers have updated and improved the double-effect technology increasing the cooling water temperature difference from the typical value of 5.5°C to 7.4°C and reducing the cooling water flow rate by about 30%. Using such a modern double effect absorption unit to replace a centrifugal chiller the same cooling water circuit can be used and the total cost of the retrofit is minimized. In this case a new flow pattern of the cooling tower is developed, and in this paper the design of a new tower fill is predicted taking into account the new factors characterizing the operating conditions and the required performance of the tower. As an example, the operational curves of a modified cooling tower (1500 KW cooling power) used by a 240 RT double-effect absorption chiller are presented.

scholarly journals Installation and Operation of a Solar Cooling and Heating System Incorporated with Air-Source Heat Pumps

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 996 ◽  
Author(s):  
Li Huang ◽  
Rongyue Zheng ◽  
Udo Piontek
Keyword(s):  
Heating System ◽  
Cooling Capacity ◽  
Heat Pumps ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Energy Yield ◽  
Absorption Chiller ◽  
Annual Average ◽  
Water Storage Tank ◽  
Solar Cooling

A solar cooling and heating system incorporated with two air-source heat pumps was installed in Ningbo City, China and has been operating since 2018. It is composed of 40 evacuated tube modules with a total aperture area of 120 m2, a single-stage and LiBr–water-based absorption chiller with a cooling capacity of 35 kW, a cooling tower, a hot water storage tank, a buffer tank, and two air-source heat pumps, each with a rated cooling capacity of 23.8 kW and heating capacity of 33 kW as the auxiliary system. This paper presents the operational results and performance evaluation of the system during the summer cooling and winter heatingperiod, as well as on a typical summer day in 2018. It was found that the collector field yield and cooling energy yield increased by more than 40% when the solar cooling and heating system is incorporated with heat pumps. The annual average collector efficiency was 44% for cooling and 42% for heating, and the average coefficient of performance (COP) of the absorption chiller ranged between 0.68 and 0.76. The annual average solar fraction reached 56.6% for cooling and 62.5% for heating respectively. The yearly electricity savings accounted for 41.1% of the total electricity consumption for building cooling and heating.

The Modeling of Air-Cooled Absorption Chiller Integration in CHP System

2004 ◽  
Author(s):  
Xiaohong Liao ◽  
Patricia Garland ◽  
Reinhard Radermacher
Keyword(s):  
Control Strategies ◽  
Lithium Bromide ◽  
Absorption Chiller ◽  
Absorption Chillers ◽  
Operation Conditions ◽  
Bromide Solution ◽  
Exhaust Heat ◽  
Lithium Bromide Solution ◽  
Prime Movers ◽  
Chp System

Absorption chillers are well suited for the use of exhaust heat from prime movers, and they improve the heat utilization of Cooling, Heating, and Power (CHP) systems. An air-cooled absorption chiller eliminates the cooling tower and brings considerable advantages as compared to water-cooled chillers. However, the expensive capital cost and crystallization of LiBr (Lithium Bromide) solution in certain operation conditions restrict the commercialization of air-cooled LiBr absorption machines. This paper discusses the feasibility of air-cooled absorption in CHP systems, where the control strategies based on the application can avoid the occurrence of crystallization. By using the fundamental thermodynamic principle, steady-state thermodynamic modeling and simulation have been done in Engineer Equation Solver (EES) to predict the operation of air-cooled absorption chiller integration in CHP systems with special consideration of the crystallization limits. The data of field operation acquired from a CHP system at UMD are used for validation.

Transient Modeling of a Lithium Bromide – Water Absorption Chiller

2013 ◽  
Vol 388 ◽  
pp. 83-90 ◽  
Author(s):  
Ang Li ◽  
Wai Soong Loh ◽  
Kim Choon Ng
Keyword(s):  
Water Absorption ◽  
Cooling Tower ◽  
Lithium Bromide ◽  
Cooling Water ◽  
Coefficient Of Performance ◽  
Absorption Chiller ◽  
Transient Model ◽  
Operation Conditions ◽  
Operation Process ◽  
Main Components

This article presents a thermodynamic framework for a lithium bromide – water absorption chiller, in which a transient model is developed to simulate the operation process. Local energy and mass balance within the main components like absorber, regenerator, condenser, evaporator and solution heat exchanger is respected to investigate the behavior of the chiller. Experimental correlations are used to predict heat transfer of the related working fluids. The cooling water is set to typical cooling tower conditions of tropical countries such as Singapore. The coefficient of performance (COP) is evaluated against a range of heat source temperatures from 75oC to 100oC. The results indicate the operation conditions of the chiller at its maximum COP is 95oC to 100oC.

Design and Modeling of One Refrigeration Ton Solar Assisted Adsorption Air Conditioning System

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
M. Alkhair ◽  
M. Y. Sulaiman ◽  
K. Sopian ◽  
C. H. Lim ◽  
E. Salleh ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Cooling Water ◽  
Cooling Capacity ◽  
Hot Water ◽  
Activated Carbon Fiber ◽  
Coefficient Of Performance ◽  
Weather Data ◽  
Adsorption System ◽  
Water Storage Tank ◽  
Chilled Water

The modeling of the performance of a one refrigeration ton (RT) solar assisted adsorption air-conditioning refrigeration system using activated carbon fiber/ethanol as the adsorbent/adsorbate pair has been undertaken in this study. The effects of hot water, cooling water, chilled water inlet temperatures, and hot water and chilled water flow rates were taken into consideration in the optimization of the system and in the design of the condenser, evaporator, and hot water storage tank. The study includes analysis of the weather data and its effect on both the adsorption system and the cooling load. This is then followed by estimation of the cooling capacity and coefficient of performance (COP) of the adsorption system as a function of the input parameters. The results of the model will be compared to experimental data in a next step.

scholarly journals Numerical Simulation of the Performance Characteristics of the Hybrid Closed Circuit Cooling Tower

2008 ◽  
Vol 13 (1) ◽  
pp. 89-101 ◽  
Author(s):  
M. M. A. Sarker ◽  
E. Kim ◽  
G. C. Moon ◽  
J. I. Yoon
Keyword(s):  
Pressure Drop ◽  
Experimental Measurement ◽  
Cooling Tower ◽  
Cfd Simulation ◽  
Air Flow ◽  
Flow Distribution ◽  
Cooling Capacity ◽  
Performance Characteristics ◽  
Closed Circuit ◽  
Flow Rates

The performance characteristics of the Hybrid Closed Circuit Cooling Tower (HCCCT) have been investigated applying computational fluid dynamics (CFD). Widely reported CFD techniques are applied to simulate the air-water two phase flow inside the HCCCT. The pressure drop and the cooling capacity were investigated from several perspectives. Three different transverse pitches were tested and found that a pitch of 45 mm had lower pressure drop. The CFD simulation indicated that when air is supplied from the side wall of the HCCCT, the pressure drop can be over predicted and the cooling capacity can be under predicted mainly due to the non-uniform air flow distribution across the coil bank. The cooling capacity in wet mode have been calculated with respect to wet-bulb temperature (WBT) and cooling water to air mass flow rates for different spray water volume flow rates and the results were compared to the experimental measurement and found to conform well for the air supply from the bottom end. The differences of the cooling capacity and pressure drop in between the CFD simulation and experimental measurement in hybrid mode were less than 5 % and 7 % respectively for the uniform air flow distribution.

Applications of Geothermal Energy in Space Cooling: A Simulator Study of Existing Oil Well to Activate an Absorption Chiller

2019 ◽  
Author(s):  
Fadi A. Ghaith ◽  
Kamal Majlab Wars
Keyword(s):  
Water Source ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Oil Field ◽  
Hot Water ◽  
Optimum Operating ◽  
Oil Well ◽  
Absorption Chiller ◽  
Space Cooling ◽  
Water Feed

Abstract This paper addresses the potential of integrating the existing oil wells and absorption chiller for the purpose of provision space cooling for the base camp of oil field at Block 9 located in Oman. The wellbore was used as a hot water feed to the chiller. Well S 347 was selected as the hot water source and well S 179 was selected to be the injection well for the outlet water. The existing wells were assessed via PIPESIM software. Using PIPESIM software, the fluid temperatures, well pressure and flow rates were obtained and analyzed throughout NODAL analyses. The water temperature of 100 °C, well head pressure of 100 psi and flow rate of 30 m3/h, were found to be the optimum operating parameters. The COP of the absorption chiller was obtained via ABSIM software. The variable operating conditions were investigated and elaborated as a function of the efficiency and capacity ratio. The designed system was configured to yield 0.733 COP and a capacity of 377 KW which met the cooling capacity of the admin building of block 9. The entire feasibility analysis was performed in terms of the overall cost as well as the saving that would be achieved from such homogeneity. The payback period of the entire system was found to be 7 years which emphasized a great potential of adapting the technology if the operating resources are available.

scholarly journals Numerical Study of Integrated Solar Photovoltaic–Thermal Module with a Refrigeration System for Air-Conditioning and Hot Water Production under the Tropical Climate Conditions of Singapore

2018 ◽  
Vol 26 (03) ◽  
pp. 1850021 ◽  
Author(s):  
Swapnil Dubey ◽  
Alison Subiantoro
Keyword(s):  
Air Conditioning ◽  
Numerical Study ◽  
Power Saving ◽  
Tropical Climate ◽  
Cooling Capacity ◽  
Hot Water ◽  
Coefficient Of Performance ◽  
Solar Photovoltaic ◽  
Refrigeration System ◽  
Climate Conditions

Thermal systems of buildings in the tropics are highly energy intensive. In this study, a novel integrated solar photovoltaic–thermal–refrigeration (PVTR) system used to produce hot water and air-conditioning in the tropical climate conditions of Singapore was analyzed. A dynamic simulation model was formulated for the analysis. Mathematical models were developed for the PV sandwich attached with a solar flat plate collector and for the main components of the refrigeration system. Thorough investigation of the electrical and thermal performances of the system were conducted through the analysis of coefficient of performance (COP), cooling capacity, water temperature and heat capacity in water heater, photovoltaic (PV) module temperature and PV efficiency. The results show that attractive electrical and thermal performance can be achieved with a maximum annual cooling COP of 9.8 and a heating COP of 11.3. The PV efficiency and power saving were 14% and 53%, respectively. The annual cooling, heating and PV energy produced were 9.7, 15.6 and 1.6[Formula: see text]MWh, respectively. The financial payback period of the system was 3.2 years and greenhouse gas (GHG) emission reduction annually was 12.6 tons of CO2 equivalents (tCO2e).

scholarly journals Investigation on the Optimum Design of Heat Exchangers in a Hybrid Closed Circuit Cooling Tower

1970 ◽  
Vol 37 ◽  
pp. 52-57
Author(s):  
MMA Sarker
Keyword(s):  
Heat Exchanger ◽  
Optimum Design ◽  
Heat Exchangers ◽  
Cooling Tower ◽  
Cooling Capacity ◽  
Closed Circuit ◽  
Design Parameters ◽  
Air Inlet ◽  
Staggered Arrangement ◽  
Temperature And Pressure

Investigation on the optimum design of a heat exchanger in a Hybrid Closed Circuit Cooling Tower having a rated capacity of 1RT is performed experimentally. The heat exchanger of dimension 0.4mx0.33mx0.572m has 15x7 bare type 15.88mm OD copper coils in staggered arrangement. The relevant design parameters were selected based on the typical East Asian meteorological constrains for the year-round smooth operation of the cooling tower. This study presents results related to the cooling capacity and the cooling efficiency with respect to wet bulb temperature and pressure drop with respect to air inlet velocity. Results are also presented in terms of number of transfer units (NTU). Cooling capacity was found to be close to the rated one for the wet mode but low in dry mode operation. Keywords: Hybrid closed circuit cooling tower, Cooling capacity, Wet mode, Dry modedoi:10.3329/jme.v37i0.820Journal of Mechanical Engineering Vol.37 June 2007, pp.52-77

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