Zacharie Tamainot-Telto

Adsorption refrigerator using monolithic carbon-ammonia pair

Abstract This paper presents the description of a laboratory prototype of an adsorption cooling machine which uses an activated monolithic carbon-ammonia pair. The design is focused on the generator consisting of aluminium and monolithic carbon discs. A numerical model of the generator based on the mass and energy conservation equations is developed. The heat transfer model (between aluminium fin and activated carbon-ammonia pair) is validated by comparing computer simulation and experimental results at ice maker operating conditions corresponding to tropical use (the evaporating and condensing temperature ranges are −20°C to 0°C and 20°C to 45°C, respectively).

Monolithic carbon for sorption refrigeration and heat pump applications

Abstract The thermophysical properties (effective thermal conductivity k, permeability K, porosity x and effective specific heat C) of two types of monolithic activated carbons are investigated with the intention of designing a high performance generator for sorption refrigeration systems and heat pumps using ammonia as refrigerant. This paper is mainly focused on the experimental procedures and results. Typical values obtained with one of the samples tested are: thermal conductivity = 0.44 W m−1 K−1, limiting concentration = 0.36 kg NH3kg−1 Carbon and carbon specific heat = 1080 J kg−1 K−1 at 100°C. The permeability results are highly anisotropic.

Advanced solid sorption air conditioning modules using monolithic carbon–ammonia pair

Abstract In order to design and build a low cost rotary regenerative adsorption air conditioning system using monolithic carbon–ammonia in a multiple bed design, three single module configurations have been tested. The basic single module named MODULAR1-0.0 consists of stainless steel tube 12.7 mm in diameter, wall thickness 0.25 mm and 600 mm long and contains about 2.6 mm layer of monolithic carbon (about 40 g) from WaterLink Sutcliffe Carbons Ltd. The far end of the module (about 230 mm long) is the evaporator–condenser (receiver). An inert material (PTFE) is inserted between the receiver and the generator as an adiabatic section that reduces the longitudinal conduction between them. From the basic module, two other module configurations (MODULAR2-0.125 and MODULAR2-0.3) are considered with external aluminium fins to improve the heat transfer capacity of the module: each consists of two basic single modules with both generator and receiver fitted with rectangular aluminium fins. This paper is focused on detailed design, construction and testing of modules. The experimental results are presented and discussed. At typical conditions (TG=100 °C, TC=30 °C and −5 °C

Solar sorption refrigerator

The performance of a solar sorption refrigerator is studied experimentally for three configurations of its collector cover: with single glazing, with double glazing and with single glazing plus transparent insulation. The collector consists of fifteen stainless steel tubes having a selective surface (with good thermal absorption coefficient) and contains granular activated carbon adsorbent with ammonia refrigerant. The collector surface area is approximately 1.43 m2 and contains about 17 kg of carbon. The collector operates with good efficiency (36 to 47% depending on conditions) when in the single glazing configuration.

Solar sorption refrigerator using a CPC collector

A prototype Compound Parabolic Concentrating (CPC) solar energy collector for a sorption refrigerator is presented. It consists of two CPC reflectors, two absorbers and a single glazing cover. The absorber is made with seamless steel tube covered in a selective surface (absorptance: 0.95) and contains aluminium fins, activated carbon and ammonia. The parabolas are manufactured from aluminium foil and a reflective microfilm is bonded on its surfaces to provide high solar reflectance (0.95). The concentration ratio of the collector is about 2.4 and corresponds to an incidence half angle of 25°. A numerical model of the absorber is described. Simulations with a daily solar radiation corresponding to tropical areas are presented.

Proof of Concept Car Adsorption Air-Conditioning System Using a Compact Sorption Reactor

A prototype compact sorption generator using an activated-carbon/ammonia pair based on a plate heat exchanger concept has been designed and built at Warwick University. The novel generator has low thermal mass and good heat transfer. The heat exchanger uses nickel brazed shims and spacers to create adsorbent layers only 4 mm thick between pairs of liquid flow channels of very low thermal mass. The prototype sorption generator manufactured has been evaluated under the European Union (EU) car air-conditioning testing conditions. While driven with waste heat from the engine coolant water (at 90°C), a pair of the current prototype generators (loaded with about 1 kg carbon in each of two beds) has produced an average cooling power of 1.6 kW with 2-kW peaks.