• Energy Research
• 6. Clean water close

The integration of a water purification system in a heat transformer allows a fraction of heat obtained by the heat transformer to be recycled, increasing the heat source temperature. Consequently, the evaporator and generator temperatures are also increased. For any operating conditions, keeping the condenser and absorber temperatures and also the heat load to the evaporator and generator, a higher value of COP is obtained when only the evaporator and generator temperatures are increased. Simulation with proven software compares the performance of the modeling of an absorption heat transformer for water purification (AHTWP) operating with water/lithium bromide, as the working fluid–absorbent pair. Plots of enthalpy-based coefficients of performance (COPET) and the increase in the coefficient of performance (COP) are shown against absorber temperature for several thermodynamic operating conditions. The results showed that proposed (AHTWP) system is capable of increasing the original value of COPET more than 120%, by recycling part of the energy from a water purification system. The proposed system allows to increase COP values from any experimental data for water purification or any other distillation system integrated to a heat transformer, regardless of the actual COP value and any working fluid–absorbent pair.

Abstract Thermodynamic equations for the performance evaluation of the monomethylamine–water vapour absorption refrigeration system have been obtained, analysed and reported in this paper. These equations have been derived from experimental data with a good agreement with the expected values and have been expressed in polynomial form. These equations were utilized on the energy and mass balances for obtaining the coefficient of performance (COP) with this pair and compared with the ammonia–water absorption system. It has been observed that this refrigerant–absorbent pair has a greater coefficient of performance at low generation temperatures and moderate condenser, absorber and evaporator temperatures.

Water is a natural resource essential for life and for most economic activities developed on earth. Population growth and lack of water in some regions of the world has led humans to design and implement new technologies to use water in an efficient way. Water quality requirements in the industrial sphere are higher everyday. Development of desalination technology through a water purification system integrated to heat pumps has taken more than two decades. Absorption heat pumps use low quality energy in a waste heat form and a small quantity of high quality energy. This characteristic has made possible using these systems in quite a few places. The following work presents the results of the experimental tests applied to a portable water purification system integrated to a heat transformer (TTAPPA), where the low quality waste heat is simulated and LiBr-water is used as a working solution.

Abstract A proposal for rational energy saving using wasted heat is showed in the present paper. Thermodynamicmathematical model is presented like an effort for water purification from waste heat. This paper describes computing results of heat transformer operation for water purification using low grade waste heat. Equations, parameters and simplifications used in the model are briefly described. The main parameter of the carried out study is the coefficient of performance (COP) defined for reversed heat pumps and the second main parameter is absorber temperature, both parameters has been showed and correlated between them. Main objective of this work is to show the optimal operating condition for different process which deliver low grade waste heat and requires water purification. Assisted computing simulation was used for obtain these results. The main conclusion is an ecological proposal for optimal recover of low grade waste heat. Many operating conditions are showed in graphical form and discussed for different environment conditions.

A reverse osmosis system driven by photovoltaic energy is an eco-friendly and sustainable way to produce freshwater in rural areas without connection to a power grid and with available brackish water sources. This paper describes a project where a photovoltaic-driven low-pressure reverse osmosis system (LPRO-PV) was designed, tested under laboratory conditions, and installed in Samalayuca, Chihuahua, Mexico, to evaluate the technical feasibility and social impact of this technology. The LPRO-PV system was tested with synthetic water with a salinity of 2921 ± 62.3 mg/L; the maximum freshwater volume produced was 1.8 ± 0.06 m3/day with a salinity value of 91 ± 1.9 mg/L. The LPRO-PV system satisfied the basic freshwater requirements for a local family of three members for one year, including the mobility-restriction period due to the COVID-19 pandemic. The social evaluation analysis reflects the importance of considering the technical aspects derived from the experimental tests, as well as the users’ perception of the performance and operation of the system. As a result of the implementation of this technology and the benefits described by the users, they committed to the maintenance activities required for the LPRO-PV system’s operation. This technology has great potential to produce fresh water in arid and isolated regions with high-salinity groundwater sources, thus fulfilling the human right to safe and clean drinking water.

Abstract In this paper, a review of the performance and development of absorption heat transformers is presented. The review covers the current state of theoretical and experimental studies of single and advanced systems, operating with conventional or alternative mixtures. It also includes their applications, such as waste heat recovery from industrial processes, cogeneration systems and seawater desalination and distillation among others. A bibliographic review has been done based on international journals, dating back from 1986 to date. The review does not intend to be exhaustive, but to reflect the most important research that has been published concerning these technologies.

Abstract The potential of the fluid mixture water-(LiBr+LiI+LiNO3+LiC1) is studied by numerical simulation for purification of seawater using single-stage absorption heat transformer. The multi-component salt mixture shows a considerably higher solubility than that of the conventional working fluid water-LiBr and it is also less corrosive. The thermal operating conditions considered in the simulation correspond to heat delivered for water purification by an absorber operating at 100°C, waste heat supplied to the generator and the evaporator operating at temperatures ranged from 60 to 80°C, heat sink cooling the condenser operating at a temperature between 10 and 40°C. The results show better performance of the integrated absorption heat transformer water purification system using the working fluid water-(LiBr+LiI+LiNO3+LiCI) compared with the system using water-LiBr. The enthalpy-based coefficient of performance is higher and remains almost constant as the condensation temperature increases at the considered thermal operating conditions of the cycle. The wider range of solubility of the multi-component salt solution makes possible the operation of the heat transformer cycle at higher concentrations of the strong solution.

A theoretical analysis of the coefficient of performance COP was undertaken to examine the efficiency characteristics of the monomethylamine–water solutions for a single-stage absorption refrigeration machine, using low generator temperatures (60–80°C), which allows the use of flat plate solar collectors. The thermodynamic analysis considers both, basic and refined cycles. The refined absorption cycle included a sensible heat recover exchanger (that is a solution heat exchanger). The thermal coefficients of performance COPh for the basis cycle and COPSHE for the refined cycle were calculated using the enthalpies at various combinations, at the operating temperatures and concentrations. The flow ratio FR has been calculated as additional optimization parameter. Due to the relative low pressure and the high coefficients of performance, the monomethylamine–water solutions present interesting properties for their application in solar absorption cycles at moderate condenser and absorber temperatures (25–35°C), with temperatures in the evaporator from −10°C to 10°C which are highly usable for food product preservation and for air conditioning in rural areas.