Novel compact sorption generators for car air conditioning

A prototype compact generator using the activated carbon-ammonia pair based on the 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 was evaluated under EU car air conditioning test conditions. The prototype sorption generator is described and its experimental performance reported. While driven with waste heat from the engine coolant water (at 90 degrees C), a pair of the current prototype generators (loaded with about 1 kg of activated carbon) operating out of phase has produced an average cooling power 1.6 kW with about 2 kW peaks. The typical average COP obtained is 0.22

Application of a compact sorption generator to solar refrigeration: case study of Dakar (Senegal)

The feasibility of applying a low cost plate heat exchanger solid sorption reactor to solar powered refrigeration is investigated by using a validated reactor model. The proposed system is targeted at ice-making in developing countries for food preservation. The adsorption refrigeration machine modelled employs the active carbon-ammonia working pair in both two-bed and four-bed regenerative systems. Driving heat is provided from standard flat plate and evacuated tube solar collectors. The capital cost of a one-off machine with four regenerative beds which could produce up to 1000 kg of ice per day in Dakar (Senegal) is estimated at €68,000

Development of a small-scale trigeneration plant based on a CI engine fuelled by neat non-edible plant oil

This study presents design and construction of a tri-generation system (thermal efficiency, 63%), powered by neat nonedible plant oils (jatropha, pongamia and jojoba oil or standard diesel fuel), besides studies on plant performance and economics. Proposed plant consumes fuel (3 l/h) and produce ice (40 kg/h) by means of an adsorption refrigerator powered from the engine waste jacket water heat. Potential savings in green house gas (GHG) emissions of trigeneration system in comparison to cogeneration (or single generation) has also been discussed

Data for Modelling and analysis of ammonia sorption reactions in halide salts

This work has focussed on the development of an accurate method for testing and modelling the reaction kinetics involved in ammonia-salt adsorption reactions, something not achieved consistently to date. A Large Temperature Jump (LTJ) test cell has been developed for testing ammonia-salt reactions in real machine conditions. A Large Temperature Jump (LTJ) test cell has been developed for testing ammonia-salt reactions in real machine conditions. This was used to validate a new approach to modelling the behaviour and simulate the performance of chemisorption machines. A derivation of the heat transfer and thermodynamic equations are presented, and a finite difference model described which has been validated for the adsorption and desorption reactions of ammonia into halide salts within a porous matrix. The model is implemented in a MATLAB® program. Large Temperature Jump (LTJ) tests have been conducted on manganese chloride and barium chloride to validate the model and to identify the physical parameters which characterise the dynamic performance of the sorbent. The manganese chloride and barium chloride were impregnated in expanded natural graphite (ENG) (SGL SIGRATHERM®) board. The ENG board gave rise to practicable samples (31.5 mm OD ø over ½” tube) undergoing a desorption reaction in under 250 seconds with the fluid temperature 15°C above the equilibrium temperature, an order of magnitude faster than observed elsewhere. A new test method has been developed enabling an accurate single heat of reaction to be identified due to reduced hysteresis, which is reported for barium and manganese chloride. The model has been validated using experimental data from LTJ tests of two geometric configurations in radial heat transfer: discs heated/cooled from the outside radius (‘tube-side’) and annuli heated from the inner radius (‘shell-side’). The empirical data obtained is a milestone towards designed and optimised salt generators

Dynamics of BaCl2-NH3 adsorption pair

To obtain accurate kinetics of adsorption pairs, dynamic tests of a composite adsorbent material (BaCl2 impregnated into a vermiculite matrix) and ammonia were performed on small samples under isothermal conditions and on a larger quantity in a laboratory scale adsorption system. The experimental results show that the size of the pressure swing plays an important role in the dynamics of adsorption pairs. This driving pressure difference affects the mass transfer of NH3 through the pores of adsorbent and therefore the performance of the complete adsorption system. A modified Linear Driving Force (LDF) model was used to fit the experimental results. It was shown that the model can predict the dynamics of both adsorption and desorption fairly well and can be used for the modelling of the adsorption system and adsorption cycles