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In this paper, the use of Metal-Organic Framework (MOF) materials as an option for the energy efficiency enhancement of HVAC systems is investigated. In particular, the possibility of using MOFs as dehumidifying materials to reduce the latent load associated with the moisture content of the airflows is studied. A literature review is proposed, highlighting the benefits of using MOFs instead of other adsorbents (e.g., silica-gel) and discussing the unique features (high water uptake capacity and low regeneration temperatures) that make MOFs a preferential desiccant. The possibility to finely tune these properties is also underlined, reporting some explicative examples. A theoretical proposal of a psychrometric transformation, to be performed in a HVAC system equipped with a MOF-Assisted Dehumidifier (MAD), is presented. This transformation is compared with a traditional one (cooling and dehumidification operated by a cooling coil with low temperatures of the coolant). The preliminary numerical simulations, conducted on a reference case study in Florence, Italy, show an estimated energy saving of 30–50%, leading us to consider the use of this technology as a very competitive one in the air-conditioning sector.

Low-and high-enthalpy geothermal resources exist throughout the African continent, but their utilization is still minimal. The rift valley area includes several high-enthalpy resource manifestations, but numerous mediumand low-enthalpy resources characterize the mainland. Geothermal resources offer a large energy potential suitable for several users. The main goal of this article is the assessment of the energy potential of the geothermal resources in Africa for direct use. The analysis of different types of medium-and low-enthalpy resources is carried out. The use of absorption cycles for cold production is considered here. A parametric analysis of the resource conditions, with special reference to the temperature level, allowed the estimation of the cooling power potential connected to the low to medium geothermal energy resources available in the African continent. On the other hand, possible end users of this resource are identified cold room storage and building cooling. The present study covers several aspects, from thermodynamic modelling to environmental analysis. The mathematical model allows the simulation of the cooling system and, through parametric analyses, the most suitable cycle characteristics are determined in compliance with the potential of the available geothermal resource. The Life Cycle Assessment (LCA) methodology is adopted for the sustainability analysis and the assessment of environmental compatibility of the proposed solutions. A parametric Life Cycle Inventory (LCI) is developed, modeling the components according to the required size for each use. The main outcome of the present work is that the low enthalpy Geothermal available in the African continent can offer significant energy savings and large environmental benefits, which may play a fundamental role in the sustainable development of this area.

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