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Adsorption heat transformers (AHTs) are considered as promising systems for upgrading waste heat to a higher temperature. The cycle operates among three temperature reservoirs: (i) heat sink at the low temperature (TL), (ii) heat source at the medium temperature (TM), and (iii) heat supply at the high temperature (TH). In the present study, the per...
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... the AQSOA-Z02 has the lowest heat exchange values, which can be attributed to the lowest uptake difference (0.04 kg/kg) and the high slope of the isosteric heat of adsorption in the operating uptake range as depicted in Fig. 7. Therefore, the AQSOA-Z01 is suitable for a smaller size AHT cycle-based adsorption system among the different zeolites and silica gel adsorbents considered in this analysis. Figure 9 depicts the UHR and CHR of the AHT cycle for different silica gel and zeolite + water vapor pair. A ++ silica gel + water vapor pair has the highest UHR and NS10 silica gel + water vapor pair has the highest CHR of the AHT cycle. ...
Citations
... The heat of adsorption in physisorption is lower than in chemisorption [86]. The heat transformer application employing adsorption materials is referred to as Adsorption Heat Transformer (AHT or AdHT) [87,88]. A recent AHT experiment reported a thermal upgrade of 20 • C was achieved for a silica gel-water vapour closed system [88]. ...
The industrial sector utilizes approximately 40% of global energy consumption. A sizeable amount of waste energy is rejected at low temperatures due to difficulty recovering with existing technologies. Thermochemical heat transformers (THT) can play a role in recovering low-temperature industrial waste heat by storing it during high supply and discharging it on demand at a higher temperature. Thus, THT will enable waste heat reintegration into industrial processes, improving overall energy efficiency and lowering greenhouse gas emissions from the industrial sector. Salt hydrate is a promising thermochemical material (TCM) because it requires a low charging temperature which can be supplied by waste heat. Furthermore, its non-toxic nature allows the implementation of a simpler and less costly open system. Despite extensive research into salt hydrate materials for thermochemical energy storage (TCES) applications, a research gap is identified in their use in THT applications. This paper aims to provide a comprehensive literature review of the advancement of THT applications, particularly for systems employing salt hydrates material. A discussion on existing salt hydrate materials used in the THT prototype will be covered in this paper, including the challenges, opportunities, and suggested future research works related to salt hydrate THT application.
... The well-known Dubinin-Astakhov (D-A) model given by Eq. (1) [70] was used for the evaluation of adsorption equilibrium data for RD SG [53], AQSOA-Z01 [54], Syloid 72FP + 57 wt% EMIM-Ac [32], PS-II [34], and GO-SSNF [35]. ...
... Adsorption isotherm profiles of the studied RD SG [53], AQSOA-Z01 [54], Syloid 72FP + 57 wt% EMIM-Ac [32], PS-II [34], GO-SSNF [35] and MOFs [55][56][57]. The isotherm data are obtained from the cited literature at 25 • C, however, at 30 • C in case of PS-II, MOF-801, alum fumarate, and MIL-100(Fe), as per availability. ...
... The adsorption equilibrium data of all the studied adsorbents can be represented by the well-known Dubinin-Astakhov (D-A) model as given by Eq. (1) [58]. It is worth mentioning that the D-A constants for Syloid [55,56] 72FP + 57 wt% Emim-Ac [55,56], PS-I, and PS-II [54,59] and all kinds of SGs [60] are obtained from the cited literatures. On the other hand, all kinds of CTFs [61][62][63], all kinds of POPs (excluding PS-I and PS-II) [64] and Ionogels (excluding Syloid 72FP + 57 wt% Emim-Ac) [57] are fitted in this study using available adsorption equilibrium data in the cited literatures. ...
The study aims to investigate the emerging adsorbents for adsorption desalination cum cooling system (ADCS) from the viewpoints of water production potential (WPP), specific cooling potential (SCP), energy required (ER), and coefficient of performance (COP). In this regard, five kinds of covalent triazine framework (CTF), five kinds of porous organic polymer (POP), and five kinds of ionogel based adsorbents are investigated as compared to five kinds of conventional silica-gel (SG) adsorbents. The well-known Dubinin-Astakhov (D-A) model, Clausius–Clapeyron equation, and ideal cycle governing equations were used to estimate adsorption equilibrium, isosteric heat of ad/desorption and the performance indicators, respectively. Among the studied adsorbents, A++, RD, Syloid 72FP + 57 wt% Emim-Ac, bipy-CTF500, and PS-II adsorbents produced relatively good results. However, nearly equivalent WPP (0.29 kg/kg/cycle) and SCP (710 kJ/kg/cycle) were estimated for A++, RD, bipy-CTF500 using ER of 2979, 2988 and 2992 kJ/kg/cycle, respectively. The PS-II adsorbent shows the WPR of 0.33 kg/kg/cycle and SCP of 790 kJ/kg/cycle using ER of 2983 kJ/kg/cycle. The performance estimated for Syloid 72FP + 57 wt% Emim-Ac found 5.6 folds higher as compared to A++ and could utilized as a potential adsorbent for ADCS. The COP of all the studied adsorbents estimated in range of 0.74 to 0.93.
