Hybrid system combining mechanical compression and thermochemical storage of ammonia vapor for cold production

Abstract

This paper studies a hybrid system for cold production consisting of a compression cycle combined with a thermochemical process by sharing the same condenser, evaporator and refrigerant fluid. The aim of this hybridization is to solve mismatch issues between the demand of cold and the source of energy (availability and/or price) with a system as compact as possible. One important side benefit is that the interaction between the compressor and the thermochemical reactor reduces the activation temperature for ammonia desorption in the thermochemical reactor. To study this interaction a quasi-steady simulation model for both storage and de-storage phases has been developed and experimentally validated by means of a small scale (approx. 300 Wh of cold storage) experimental bench with ammonia as refrigerant and barium chloride (BaCl2) as reactant salt. Experiments proved a 35 K reduction in the activation temperature of the desorption reaction with respect to desorption without compressor. Model validation by adjusting permeability and thermal conductivity of the reactive composite showed an acceptable agreement between predicted and experimental reaction advancement-time curves. The validated model was used for simulation of the system in a preliminary case study, representative in power (40 kW) and temperature (-25°C) of an industrial cold demand. It is shown that during ammonia de-storage, the hybrid achieves a higher COP than a conventional mechanical vapor compression system. It increases exponentially with the relative share of thermochemical storage in the cold production.

A Review of Thermochemical Energy Storage Systems for Power Grid Support

“…PtH technologies show a mature development with latent and sensible storage while only a limited number of applications with thermochemical storage is available in literature [310][311][312][313][314][315][316][317]. Existing applications focus on different aspects, hence a net comparison was not possible.…”

“…[320] analyzed an ammonia-based refrigeration system consisting in the hybridization Figure 6. PtH/TCTES system developed by Ferrucci et al [173] and by Fitò et al [315].…”

“…Fitò et al [315] analyzed an ammonia-based refrigeration system consisting in the hybridization of compression refrigeration with thermochemical storage. The proposed hybrid system has the typical architecture of a MVC cycle (evaporator, compressor, condenser, reservoir and throttling valve), a grid-connected photovoltaic installation and a thermochemical storage reactor.…”

Comparative Analysis of 3D Graphene–LiOH·H2O Composites by Modification with Phytic Acid and Ascorbic Acid for Low‐Grade Thermal Energy Storages

“…[11] TCS, which can upgrade the stored heat at an arbitrary temperature with high heat storage densities, [12][13][14][15] and no heat loss, [16] is more suitable for efficient utilization of low-grade thermal energy. There are many literature that have described the adsorption process of metal salts with water, [17][18][19][20] ammonia, [21][22][23][24][25] methanol, [26][27][28] or metal alloys, [29,30] for utilizing low-grade thermal energy. Among all the reaction systems, the inorganic hydrate lithium hydroxide monohydrate (LiOH•H 2 O) due to its high energy density (1440 kJ kg À1 ) and mild reaction process was selected as the promising candidate for low-temperature (below 373 K) heat storage.…”

Optimal design and operation of ammonia decomposition reactors

“…The main advantages of using ammonia‐based systems are an existing base of industrial knowledge of ammonia and the fact that the nitrogen and hydrogen gas storage mediums are both abundant resources. Also, the reaction is free from complex side reactions and takes place at temperatures relatively easily to obtain by using solar or nuclear sources or by using hybrid and energy integrated systems . Further details about the role of ammonia in the hydrogen economy or for the storage and transport of energy may be found in Section S0 of the Electronic Supplementary Material (ESM).…”