Design, evaluation and recommedation effort relating to the modification of a residential 3-ton absorption cycle cooling unit for operation with solar energy

The possible use of solar energy powered absorption units to provide cooling and heating of residential buildings is studied. Both, the ammonia-water and the water-lithium bromide cycles, are considered. It is shown that the air cooled ammonia water unit does not meet the criteria for COP and pump power on the cooling cycle and the heat obtained from it acting as a heat pump is at too low a temperature. If the ammonia machine is water cooled it will meet the design criteria for cooling but can not supply the heating needs. The water cooled lithium bromide unit meets the specified performance for cooling with appreciably lower generator temperatures and without a mechanical solution pump. It is recommeded that in the demonstration project a direct expansion lithium bromide unit be used for cooling and an auxiliary duct coil using the solar heated water be employed for heating

Solar heating and cooling demonstration project at Radian Corporation, Austin, Texas

The solar heating and cooling system located at the Radian Corporation, Austin, Texas, is discussed. A technical description of the solar system is presented. The costs of the major components and the cost of installing the system are described. Flow diagrams and photographs of the solar system are provided

Synthesis of novel room temperature chiral ionic liquids. application as reaction media for the heck arylation of aza-endocyclic acrylates.

New achiral and chiral RTILs were prepared using novel and/or optimized synthetic routes. These new series of imidazolinium, imidazolium, pyridinium and nicotine-derived ionic liquids were fully characterized including differential scanning calorimetry (DSC) analysis. The performance of these achiral and chiral room temperature ionic liquids (RTILs) was demonstrated by means of the Heck arylation of endocyclic acrylates employing arenediazonium salts and aryl iodides. The Heck arylations performed in the presence of these ionic entities, either as a solvent or as an additive, were effective leading to complete conversion of the substrate and good to excellent yield of the Heck adduct. In spite of the good performances, no asymmetric induction was observed in any of the cases studied. Two new diastereoisomeric NHC-palladium complexes were prepared in good yields from a chiral imidazolium salt and their structure characterized by X-ray diffraction. Overall, the Heck arylations employing arenediazonium tetrafluoroborates in RTILs were more effective than the traditional protocols employing aryl iodides in terms of reactivity and yields

Characterization of a Li-6 loaded liquid organic scintillator for fast neutron spectrometry and thermal neutron detection

The characterization of a liquid scintillator incorporating an aqueous solution of enriched lithium chloride to produce a scintillator with 0.40% Li-6 is presented, including the performance of the scintillator in terms of its optical properties and neutron response. The scintillator was incorporated into a fast neutron spectrometer, and the light output spectra from 2.5 MeV, 14.1 MeV, and Cf-252 neutrons were measured using capture-gated coincidence techniques. The spectrometer was operated without coincidence to perform thermal neutron measurements. Possible improvements in spectrometer performance are discussed.Comment: Submitted to Applied Radiation and Isotopes. 11 pages, 7 figures, 3 tables. Revision addresses reviewers' comment

The development and calibration of a generic dynamic absorption chiller model

Although absorption cooling has been available for many years, the technology has typically been viewed as a poorly performing alternative to vapour compression refrigeration. Rising energy prices and the requirement to improve energy efficiency is however driving renewed interest in the technology, particularly within the context of combined cooling, heat and power systems (CCHP) for buildings. In order to understand the performance of absorption cooling, numerous models are available in the literature. However, the complexities involved in the thermodynamics of absorption chillers have so far restricted researchers to creating steady state or dynamic models reliant on data measurements of the internal chiller state, which require difficult-to-obtain, intrusive measurements. The pragmatic, yet fully-dynamic model described in this paper is designed to be easily calibrated using data obtained from the measurements of inflows and outflows to a chiller, without resorting to intrusive measurements. The model comprises a series of linked control volumes featuring both performance maps and lumped mass volumes, which reflect the underlying physical structure of the device. The model was developed for the ESP-r building simulation tool. This paper describes the modelling approach, theory and limitations, along with its calibration and the application of the model to a specific example

Gels as battery separators for soluble electrode cells

Gels are formed from silica powders and hydrochloric acid. The gels are then impregnated into a polymeric foam and the resultant sheet material is then used in applications where the transport of chloride ions is desired. Specifically disclosed is the utilization of the sheet in electrically rechargeable redox flow cells which find application in bulk power storage systems

Scheduling of Multiple Chillers in Trigeneration Plants

The scheduling of both absorption cycle and vapour compression cycle chillers in trigeneration plants is investigated in this work. Many trigeneration plants use absorption cycle chillers only but there are potential performance advantages to be gained by using a combination of absorption and compression chillers especially in situations where the building electrical demand to be met by the combined heat and power (CHP) plant is variable. Simulation models of both types of chillers are developed together with a simple model of a variable-capacity CHP engine developed by curve-fitting to supplier’s data. The models are linked to form an optimisation problem in which the contribution of both chiller types is determined at a maximum value of operating cost (or carbon emission) saving. Results show that an optimum operating condition arises at moderately high air conditioning demands and moderately low power demand when the air conditioning demand is shared between both chillers, all recovered heat is utilised, and the contribution arising from the compression chiller results in an increase in CHP power generation and, hence, engine efficiency

Parameters affecting the efficiency of a heat transformer with a particular focus on the heat solution

The heat transformer is a reverse cycle absorption machine, suitable for the direct exploitation of heat wastes and solar energy. Part of these wastes are “transformed” into thermal energy at a higher temperature than the one provided. Hence some studies concern the evaluation of the performances of the working fluids used. They must ensure a high level of efficiency which, as for the conventional absorption machines, depends on several parameters. One of these parameters is the heat solution: it is defined as the heat absorbed when a mole of a given component is mixed with the amount of the other component required to generate the desired solution at a certain temperature and pressure. This is the reason why the decision was to examine its influence with respect to machines exerting two different fluids which are generally used. The first one is NH3-H2O, whereas the second is H2O-LiBr; they used as refrigerating substances ammonia and water respectively and as absorption substances water and lithium bromide. Through an analytical modeling and the processing of experimental data provided by the bibliography, it was possible to show how, for these fluids, the terms of the sensible heat represent a moderate fraction of the global energy balance, at one condition though: highly efficient recovery exchangers must be present. Moreover there were reported values of the refrigeration effect of the order of thousands of kJ/kg with satisfying responses energetically speaking. Then a high stability of the fluid NH3-H2O was revealed, as testified by the high value of the difference between the concentration of the refrigerator in the absorber and the concentration of the refrigerator in the generato