This work concerns a modeling of habitat equipped with an adsorption cooling unit powered by a geothermal heat pump in the context of the climate of the Comoros Islands. Cooling unit is a simple system consisting of an adsorber, condenser and evaporator. The modeling of the habitat-air conditioning system was based on a description of heat and mass transfers. The first law of thermodynamics on the energy conservation using the analogies between heat and electrical transfers is used to establish the equations of the model. Zeolite-methanol pair and Dubinin-Astakhov adsorption model are used to describe the amount of adsorbed mass. The finite difference method applied to a point of the considered exchange surface is used to discretize equations and resolve them. The coupling of the system takes place through a convective transfer between the air inside habitat and the evaporator's surface. This article presents results for typical November days in Comoros. Different temperatures of habitat with and without a cooling unit show that using the adsorption cooling unit can help lower internal temperatures. We observe a temperature difference of 2.14 K in particular at 2 p.m., if the air conditioning starts at 8 a.m. The influence of the input parameters on the air inside the habitat makes it possible to assess the impact on indoor comfort. The COP th can reach 0.46. However, we can get a high performance if we optimize temperature thresholds. These show that this type of cooling unit can help improve the habitat thermal comfort in a tropical and dry climate.

This work is a contribution of a modelling of air conditioner by adsorption for a habitat in a tropical climate. The system mainly consists of a captor adsorber powered by a geothermal pump, a condenser and an evaporator. We use the zeolite/methanol couple and the different thresholds temperatures to define the thermodynamic system cycle. Moreover, we use a methodology based on nodal approach to establish heat and mass transfer equations. Dubinin-Astakhov thermodynamic model is employed to express the mass adsorbed, the coefficient of performance (COP) and the cold production. We make use of the climatic data in Comoros for 2009-2019 period to obtain the ambient temperature. The model validation is done by comparing the shape of the cycle we obtain with the state of the art. First, the results show a relationship between temperature, pressure and adsorbed mass. The increase in temperature is accompanied by an increase of pressure and an increase of adsorbed mass, and in the same way a decrease in the temperature causes a decrease of the pressure as well as a decrease of adsorbed mass. The mixture zeolite/methanol reaches 356K at the regeneration temperature with an input water temperature of 363K. We observed the influence of main important parameters on the mixture temperature such as fluid input temperature, fluid velocity or zeolite thermal conductivity. Finally, we show the thresholds temperatures influence on the COP and the cold production at evaporator.

This paper presents a numerical study of the air-conditioning of a room by a two-phase thermosyphon loop using meteorological data from the Mamou region (Guinea). The room is composed of a rectangular roof and a passenger compartment in the form of a parallelepiped. In addition, the air-conditioning unit that operates with methanol is composed of an evaporator, a condenser, a riser and a downcomer. The heat transfer modelling governing the habitat model and the air conditioning loop is based on the nodal method. The coupling of the system is done by convective transfer between the internal air of the habitat and the surface of the evaporator. The equations are solved by the implicit finite difference method. Thus, this resolution made it possible to determine the influence of the parameters on the model. This work presents results of the habitat with and without the air-conditioning loop for typical days in March of Mamou. These results show that the use of the air conditioning loop can contribute to lowering the internal air temperature. The value of the maximum temperature of the indoor air of the habitat with the air conditioner is about 299 K while that of the air without air conditioner is about 303 K. The variation of parameters such as temperature, wall thickness, incident solar flux, air exchange rate and evaporator surface has a significant impact on the operation of the air conditioner and on the temperature of the conditioned room. A low wall thickness or a high air exchange rate contributes to the temperature increase in the room. For a wall thickness of 10 cm, 15 cm or 40 cm, the air temperatures are 301.5 K, 297 K and 296.9 K respectively. However, for a habitat without an air conditioner the temperature is 303 K when the wall thickness is 15 cm.

The two-phase thermosyphon loop is an efficient solution for space cooling. This paper presents the simulation results of numerical studies on the heat transfer and thermal performance of a two-phase thermosiphon loop for passive air-conditioning of a house. The fluid considered in this study is methanol, which is compatible with copper and is environmentally friendly. These numerical results show that the temperature at the evaporator wall drops from 23˚C to 13˚C and increases at the condenser. The solar flux density has a strong influence on the condenser temperature. The mass flow rates and masses at the evaporator and condenser increase with temperature. The variation of evaporating and condensing temperature affects the performance of the system. For a constant evaporating and condensing temperature of 2˚C and 29˚C, the COP is 0.77 and 0.84 respectively. With these results, the use of the two-phase thermosyphon loop in air conditioning is possible to obtain a thermal comfort of the occupants acceptable by the standards but with a large exchange surface of the evaporator.