Thermodynamic Analysis of the New Adsorption Cycle “HeCol” for Ambient Heat Upgrading: Ideal Heat Transfer

An Aqueous CaCl2 Solution in the Condenser/Evaporator Instead of Pure Water: Application for the New Adsorptive Cycle “Heat from Cold”

“…A new cycle "Heat from Cold" (HeCol) has recently been proposed for upgrading the ambient heat in cold countries [14]. The useful heat of this cycle essentially increases at lower temperature of the ambient air [15], which is far below 0 • C. For this reason, methanol was used as a working fluid for the first theoretical and experimental investigations of the HeCol cycle. These studies confirmed that the cycle is feasible; however, its specific useful heat is restricted by 300-400 J/g_adsorbent [17] due to the relatively low evaporation heat of methanol.…”

“…The glycol remains in the evaporator and, hence, water is used as a refrigerant. For the first theoretical [15] and experimental [16,17] studies of the HeCol cycle, methanol was used as an adsorptive because of its low freezing temperature. These studies demonstrated that the proposed HeCol cycle is feasible and the generated useful heat can be suitable for heating low-energy buildings in countries with a cold climate (northern parts of Canada, Europe, Russia, the USA, etc.…”

“…It leads to the enhanced size of HeCol units, which, in its turn, increases inert thermal masses [18] of a HeCol unit and can further reduce the COP and the useful heat. Therefore, it is worthy of performing a thermodynamic evaluation of the HeCol useful heat, if water Energies 2020, 13, 2904 3 of 11 would be used as adsorptive, and compare it with that with methanol [15,17]. In this hypothetical analysis (Section 2), we neglect ice formation in the condenser.…”

Thermodynamic Analysis of Working Fluids for a New “Heat from Cold” Cycle

“…A brief overview of the thermodynamic properties of these alternative working fluids is given in Table 1. Methanol was used as an adsorptive in the first theoretical [13] and experimental [11,14,15] studies of the HeCol cycle. These studies confirmed that the non-isothermal HeCol cycle could, in principle, be implemented, and the temperature level of generated useful heat can be suitable for heating (T 3 > 35 • C).…”