Development of Corrosion Inhibitors for Absorption Heat Pumps

2002 ◽  
Author(s):  
C. L. Hannon ◽  
J. Gerstmann ◽  
F. B. Mansfeld ◽  
Z. Sun
Keyword(s):  
Water Absorption ◽  
Corrosion Inhibitors ◽  
Earth Metal ◽  
Heat Pumps ◽  
Generation Rate ◽  
Sodium Chromate ◽  
Gas Generation ◽  
Ammonia Water ◽  
Steel Surfaces ◽  
Gas Generation Rate

This paper describes the results of a research project to develop a non-toxic corrosion in hibitor for the protection of carbon steel surfaces of ammonia-water absorption heat pumps through the use of rare earth metal salt (REMS) compounds. Chromate compounds are currently used as corrosion inhibitors in these systems, but are toxic, environmentally harmful, and their use is being phased out. Corrosion concerns in ammonia-water absorption systems are primarily those of non-condensable (NC) gases generated by corrosion reactions impeding the heat and mass transfer processes in the system. The research focused on the development of a dual-protection REMS based strategy of applying a cerium-oxide/hydroxide coating to the metal surface in a process called cerating, in conjunction with a cerium-sulfate solution-based inhibitor. A laboratory test was conducted in test rigs designed to simulate the conditions of temperature and ammonia concentration found in the desorber component of advanced ammonia-water absorption systems. The test compared the NC gas generation rate in a rig with cerated steel surfaces to a rig using sodium chromate as a solution based inhibitor. The cerated test rig demonstrated an NC gas generation rate about 3 times lower than that of the chromate protected rig. Neither rig showed any indications of significant corrosion activity. This work has shown that cerating can provide superior suppression of NC gas generation in ammonia-water absorption systems compared to sodium chromate, in a process that is simple and readily applicable to the commercial manufacture of equipment.

Development of Improved Corrosion Inhibitors for Ammonia-Water Absorption Heat Pumps

2000 ◽  
Author(s):  
C. L. Hannon ◽  
J. Gerstmann ◽  
F. B. Mansfeld ◽  
Z. N. Sun
Keyword(s):  
Water Absorption ◽  
Corrosion Inhibitor ◽  
Corrosion Protection ◽  
Corrosion Inhibitors ◽  
Heat Pumps ◽  
Ammonia Decomposition ◽  
Screening Tests ◽  
Ammonia Water ◽  
Surface Pretreatment ◽  
Steel Surfaces

Abstract This paper describes the initial results of a research project to develop an improved corrosion inhibitor for the protection of carbon steel surfaces of ammonia-water absorption heat pumps and chillers using rare earth metal salt (REMS) compounds. Chromate compounds are currently used as corrosion inhibitors, but they are toxic, environmentally harmful, and their use is being phased out in many localities. An effective corrosion inhibitor is needed to make advanced ammonia-water absorption heat pump and chiller systems practical. Low-temperature screening tests were conducted to evaluate the potential of cerium salts, a class of REMS compounds, to act as an inhibitor for steel in ammonia-water solutions. Successful results from these tests led to high-temperature (HT) testing in an innovative test apparatus, which simulated a range of temperatures, ammonia concentrations, and phases typically found in ammonia-water absorption systems. HT testing further demonstrated the effectiveness of cerium nitrate as a corrosion inhibitor, and suggested that it may outperform the Chromate compounds currently used. An additional outcome of the project was the successful demonstration of a cerium based surface pretreatment procedure, termed cerating, as an additional corrosion protection feature. Cerated surfaces will prevent corrosion of steel surfaces and ammonia decomposition at steel surfaces. These results have lead to the concept of a dual corrosion protection strategy utilizing a cerium based solution inhibitor with a cerating surface pretreatment to prevent both corrosion and ammonia decomposition. This approach is presently being pursued in a more intensive study.

scholarly journals Identification of Existing Challenges and Future Trends for the Utilization of Ammonia-Water Absorption–Compression Heat Pumps at High Temperature Operation

2021 ◽  
Vol 11 (10) ◽  
pp. 4635
Author(s):  
Marcel Ulrich Ahrens ◽  
Maximilian Loth ◽  
Ignat Tolstorebrov ◽  
Armin Hafner ◽  
Stephan Kabelac ◽  
...  
Keyword(s):  
High Temperature ◽  
Water Absorption ◽  
Industrial Sector ◽  
Heat Pumps ◽  
Working Fluid ◽  
Large Temperature ◽  
Future Trends ◽  
Ammonia Water ◽  
Starting Point ◽  
High Temperature Operation

Decarbonization of the industrial sector is one of the most important keys to reducing global warming. Energy demands and associated emissions in the industrial sector are continuously increasing. The utilization of high temperature heat pumps (HTHPs) operating with natural fluids presents an environmentally friendly solution with great potential to increase energy efficiency and reduce emissions in industrial processes. Ammonia-water absorption–compression heat pumps (ACHPs) combine the technologies of an absorption and vapor compression heat pump using a zeotropic mixture of ammonia and water as working fluid. The given characteristics, such as the ability to achieve high sink temperatures with comparably large temperature lifts and high coefficient of performance (COP) make the ACHP interesting for utilization in various industrial high temperature applications. This work reviews the state of technology and identifies existing challenges based on conducted experimental investigations. In this context, 23 references with capacities ranging from 1.4 kW to 4500 kW are evaluated, achieving sink outlet temperatures from 45 °C to 115 °C and COPs from 1.4 to 11.3. Existing challenges are identified for the compressor concerning discharge temperature and lubrication, for the absorber and desorber design for operation and liquid–vapor mixing and distribution and the choice of solution pump. Recent developments and promising solutions are then highlighted and presented in a comprehensive overview. Finally, future trends for further studies are discussed. The purpose of this study is to serve as a starting point for further research by connecting theoretical approaches, possible solutions and experimental results as a resource for further developments of ammonia-water ACHP systems at high temperature operation.

scholarly journals Thickness-dependent photoelectrochemical properties of a semitransparent Co3O4 photocathode

2018 ◽  
Vol 9 ◽  
pp. 2432-2442 ◽  
Author(s):  
Malkeshkumar Patel ◽  
Joondong Kim
Keyword(s):  
Water Splitting ◽  
Water Oxidation ◽  
Hydrogen Generation ◽  
Hydrogen Gas ◽  
Generation Rate ◽  
Alkaline Electrolyte ◽  
Stoichiometric Ratio ◽  
Gas Generation ◽  
Pec Cells ◽  
Gas Generation Rate

Co3O4 has been widely studied as a catalyst when coupled with a photoactive material during hydrogen production using water splitting. Here, we demonstrate a photoactive spinel Co3O4 electrode grown by the Kirkendall diffusion thermal oxidation of Co nanoparticles. The thickness-dependent structural, physical, optical, and electrical properties of Co3O4 samples are comprehensively studied. Our analysis shows that two bandgaps of 1.5 eV and 2.1 eV coexist with p-type conductivity in porous and semitransparent Co3O4 samples, which exhibit light-induced photocurrent in photoelectrochemical cells (PEC) containing the alkaline electrolyte. The thickness-dependent properties of Co3O4 related to its use as a working electrode in PEC cells are extensively studied and show potential for the application in water oxidation and reduction processes. To demonstrate the stability, an alkaline cell was composed for the water splitting system by using two Co3O4 photoelectrodes. The oxygen gas generation rate was obtained to be 7.17 mL·h−1 cm−1. Meanwhile, hydrogen gas generation rate was almost twice of 14.35 mL·h−1·cm−1 indicating the stoichiometric ratio of 1:2. We propose that a semitransparent Co3O4 photoactive electrode is a prospective candidate for use in PEC cells via heterojunctions for hydrogen generation.

Study on the Kinetics and Pyrolysis Behavior of Waste Containing Urea-Formaldehyde Resins

2020 ◽  
Vol 14 (4) ◽  
pp. 444-452
Author(s):  
Ling Fang ◽  
Lin Liu ◽  
Siyi Luo ◽  
Junzhi Wang ◽  
Zongliang Zuo ◽  
...  
Keyword(s):  
Reaction Order ◽  
Urea Formaldehyde ◽  
Coupled System ◽  
Generation Rate ◽  
Formaldehyde Resin ◽  
Gas Generation ◽  
Wood Panel ◽  
Gaseous Products ◽  
Gas Generation Rate ◽  
Theoretical Evidence

In this work, we studied the kinetics and behavior of wood panel wastes containing ureaformaldehyde resins. For this purpose, we used a TG-FTIR coupled system to analyze the gaseous products of the pyrolysis. With the results, we obtained the models that provide theoretical evidence and data support for the studied reactions. According to our findings, the pyrolysis of the ureaformaldehyde components displayed two stages, and the second stage presented a higher intensity. At a temperature of 900 °C, the gas generation rate for hard UF (UF1) was 32.6% higher than that for soft UF (UF2). When temperature increased from 600 °C to 900 °C, the increase of the gas generation rate was relatively small. In addition, the reaction order was obtained using the CoatsRedfern method, which provided a value for the reaction order of 1.4. The activation energy of UF1 was slightly higher than that of UF2. The FTIR analysis indicated that the main gaseous products of the pyrolysis of the urea-formaldehyde resin samples were CO2, H2O, and other compounds containing the C–H and the N–H bond as well as carbonyl groups. In addition, it was determined that Nitrogen was mainly present in the form of hydronitrogen compounds but not as nitrogen oxides. These last may represent a higher degree of pollution.

Microchannel component technology for system-wide application in ammonia/water absorption heat pumps

2011 ◽  
Vol 34 (5) ◽  
pp. 1184-1196 ◽  
Author(s):  
Srinivas Garimella ◽  
Matthew D. Determan ◽  
J. Mark Meacham ◽  
Sangsoo Lee ◽  
Timothy C. Ernst
Keyword(s):  
Water Absorption ◽  
Heat Pumps ◽  
Component Technology ◽  
Ammonia Water

scholarly journals Factors Influencing Gas Generation Behaviours of Lump Coal Used in COREX Gasifier

2019 ◽  
Vol 38 (2019) ◽  
pp. 30-41
Author(s):  
Runsheng Xu ◽  
Jianliang Zhang ◽  
Wei Wang ◽  
Haibin Zuo ◽  
Zhengliang Xue
Keyword(s):  
Particle Size ◽  
Energy Conservation ◽  
Mass Loss ◽  
Reduction Potential ◽  
Generation Rate ◽  
Coal Rank ◽  
Gas Generation ◽  
Factors Influencing ◽  
Gas Generation Rate ◽  
Lump Coal

AbstractThe influences of coal rank, particle size, temperature and gasifier atmosphere on the gas generation of lump coals used in COREX gasifier were investigated. The results showed that an increase in gasifier temperature and a decrease in particle size hardly affected the final mass loss of lump coals but strongly enhanced the gas generation rate. When the temperature was greater than 1000 °C, a decrease in coal rank increased the gas yield but had little effect on the gas generation rate. Moreover, the promotion ability of the atmosphere for the gas generation rate of lump coal from low to high was as follows: N2, CO2, CO and H2. Considering energy conservation, to improve the gas generation rate of the gasifier, the coal rank and particle size should be decreased first, and afterwards, an increase in reduction potential of the atmosphere in gasifier is also encouraged.

Improved Hydrogen Gas Generation Rate of n-GaN Photoelectrode with SiO[sub 2] Protection Layer on the Ohmic Contacts from the Electrolyte

2010 ◽  
Vol 157 (2) ◽  
pp. B266 ◽  
Author(s):  
Shu-Yen Liu ◽  
J. K. Sheu ◽  
Chun-Kai Tseng ◽  
Jhao-Cheng Ye ◽  
K. H. Chang ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Hydrogen Gas ◽  
Generation Rate ◽  
Gas Generation ◽  
Protection Layer ◽  
Gas Generation Rate
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