New Residential Water Heater Concept Promises high Efficiency, Lower Cost

In the Vol. 34, No 2/2016 edition o f the IEA Heat Pump Conference, the foundation of our semi-open absorption technology in a hybrid application is discussed. The link to the article is:

https://issuu.com/hptmagazine/docs/hpt_magazine_no2_2016?e=24860023/39632266

Nanoengineered Membrane-based Absorption Refrigeration System

Absorption refrigeration systems (ARSs) dominated the refrigeration industry for much of the 19th century. Increased access to electricity in the later part of that century triggered gradual replacement of the ARSs with the vapor-compression systems (VCSs). The higher performance per unit cost, lower volume per unit cooling capacity, and favorable operational and maintenance characteristics of the VCSs fueled their vast market penetration particularly in the residential air conditioning sector. Despite their great advantages, VCSs consume significant electrical energy and use refrigerants that are not environment friendly. Significant increase in the demand for air conditioning in developing countries, rise in fuel costs, and environmental impacts of power production cycles have raised concerns about the long-term sustainability of the living standard this technology has offered to the world population. Thus, development of alternative more efficient technologies with less environmental impact is of great interest.

ARSs could play a larger role in the future cooling market if compact, inexpensive, high performance, and robust systems are developed. Such systems are particularly attractive in combined heating, cooling and power (CCHP) systems where in the ARS is powered by waste heat. Recent advancements in solar-thermal collectors have also enhanced the prospect of solar-cooling using ARSs. Hybrid systems powered by solar energy and natural gas could conceivably provide year-round cooling, space heating, and hot water to a building. Implementation of such a system could enhance fuel efficiency and utilization of renewable energy and reduce the electrical grid load during the peak demand for air conditioning.

Among the different heat-powered cooling cycles LiBr-water deliver the highest performance using low quality heat (100 to 200 °C). A double-effect LiBr-water system can deliver a primary COP of 1.2-1.3, which can match or exceed the primary COP of a typical VCS. Primary COP factors in a multiplier for the primary energy consumption (a multiplier of 3.18 is used in US corresponding to an average power production efficiency of 31.4%). Despite their great performance, LiBr-water systems are not economical at small scales. A typical absorption refrigeration system (ARS) consists of large heat exchangers (HXs) that constitute most of the system size and cost. In this work, nanoengineered membranes are implemented to greatly enhance the transport processes involved within the system and reduce the HXs size and cost. The membrane-based HXs are integrated together into new configurations with significantly higher surface area per volume compare to the existing technology. The new system configuration along with the advance material and manufacturing technologies that the new generation ARS benefits from promise an inexpensive, reliable, and low maintenance ARS.

In a conversation with TechConnect News, Dr. Saeed Moghaddam stated that their novel approach to the design of heat exchangers is promising a reduction in size and, therefore, material usage of 1 to 2 orders of magnitude.  Dr. Moghaddam and his team in Nanostructured Energy System Laboratories (NESLabs) at the University of Florida have conducted extensive experimental studies over the past two years and have shown that their concept works. Dr. Moghaddam further stated that at this point realization of the technology in the market place depends on cost-effective manufacturing of the HXs. They are currently building systems with 1-2 Ton refrigeration capacity and expect a prototype within 1.5 years.

Visit http://http://www2.mae.ufl.edu/saeedmog/ to to learn more about Dr. Moghaddam’s research.

Written by: Susan Stewart 12 December 2012, Nano Science and Technology Institute News

Solar Thermal Energy Could Keep Buildings Cool

A University of Florida engineering researcher has received $1 million in federal stimulus funds for a research project aimed at developing small refrigeration systems powered by solar thermal energy or waste heat. If successful, solar-powered cooling and heating of residential buildings could become economically viable.

Assistant Professor Saeed Moghaddams project was among 43 green energy projects funded with $92 million in stimulus funds from the U.S. Department of Energys Advanced Research Projects Agency.

University of Floridas Nanostructured Energy Systems group, directed by Moghaddam, is developing small-scale absorption refrigeration systems that, with reasonable efficiency, harness low-quality heat energy that cannot be converted to electricity. The systems use refrigerants such as water that have no global warming potential.

Absorption refrigeration systems have long been used to convert heat to a cooling effect but have been limited to large scales (hundreds of tons), where the economy of scale justifies their high cost and the boilers and cooling towers they require.

Moghaddam says that two-thirds of the fuel energy used for generating electricity is being wasted in the form of waste heat. And solar energy is only 10 to 15% efficient, with the rest mostly turning into waste heat. Absorption refrigeration systems could use this waste heat or could be powered by solar thermal energy, but manufacturing low-cost, small, and robust systems has been a challenge.

Economically viable solar-powered absorption refrigeration systems for buildings have the potential to harness solar thermal energy with efficiencies of 50 to 70%, far beyond the reach of photovoltaic cells, says Moghaddam. An inexpensive small-scale absorption refrigeration system coupled with solar collectors and a natural gas-fired heater could provide an economically viable route for year-round cooling, heating, and hot water generation in typical buildings while also reducing energy demand and greenhouse gas emission

Written by: Nancy Lamontage 22 July 2010,  Solar Novus Today

New Membrane Based ARS

Critical Need: Development of an inexpensive and high performance heat-powered cooling system greatly expands utilization of solar-thermal energy and low-grade waste heat for cooling buildings and process fluids and improves the economics of energy efficient combined cooling, heat, and power (CCHP) systems. Two-thirds of the fuel used in the world is wasted in the form of heat. Solar energy is harnessed with only close to 20% efficiency and the rest becomes waste heat. Thus, efficient utilization of low quality heat has a revolutionary impact on our future energy economy and carbon emission.

Project Innovations + Advantages: Absorption refrigeration systems (ARS) are fundamentally attractive for our future energy economy because they can convert low quality heat energy to cooling at the highest efficiency compare to other technologies.
 
A typical ARS consists of large heat exchangers that constitute most of the system size and cost. The transport processes within the heat exchangers are responsible for their bulkiness. In this work, nanoengineered membranes are implemented to greatly enhance the transport processes. The membrane-based heat exchangers are integrated together into new configurations with significantly higher surface area per volume compare to the existing technology. The new system configuration along with the advance material and manufacturing technologies that the new generation ARS benefits from promise an inexpensive, reliable, and low maintenance ARS.

The latest experimental data on laboratory-scale system elements suggest that the heat exchangers of a high performance ARS can be made at an order of magnitude smaller size and cost compare to the existing systems. Also, the volume of the Li-Br solution in the new generation system is an order of magnitude less than that of the existing systems.