Two or more than two outputs from a single source result an overall high energy utilization factor (EUF) compared to the single output system. In this work, two stage humidification and dehumidification (HDH) desalination system has been extended with cooling system integration. Solar flat plate collector and concentrating collector are selected respectively for HDH desalination and single effect vapor absorption refrigeration (VAR) plant. The cooling after desalination increases the yield of distillation compared to without its integration. The sequence of operations in the combined plant is first stage air preheatinghumidification-dehumidification, second stage air preheating-humidification-dehumidification and final cooling of air with chilled water. The work is aimed on thermodynamic study for maximization of EUF for cycle and plant. The role of humidifier efficiency, its effectiveness, hot water temperature and chilled water temperature (by varying VAR evaporator temperature) has been studied on integrated performance. The resulted distilled water is 670 LPH with 75kW cooling at unit volume of air (1m3/s). The cycle EUF and plant EUF are 0.58 and 0.33 respectively. © 2014 Elsevier B.V.

Chiranjeevi C

Department of Thermal and Energy Engineering

School of Mechanical Engineering

Vellore Campus

Srinivas T.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

&nbsp;

&nbsp;

VIT University

Desalination

Waste heat rejection to ambient from air conditioning systems is one of the major causes of urban heat island effect. Increased urbanization and living standards leads to increased water demand. In this work, a new design of vapor compression refrigeration system integrated with humidification-dehumidification desalination is proposed without changing the actual size of vapor compression refrigeration system. The present system consists of a compressor, an evaporative condenser, an expansion device, an evaporator and a suction fan. Water to be desalinated is sprayed over the evaporative condenser. The evaporative condenser and the evaporator are also acting as humidifier and dehumidifier of humidification-dehumidification desalination. In order to recover waste heat rejected to ambient, cooling of evaporative condenser using indoor air and subsequent condensation of hot humid air in evaporator is proposed in this work. The proposed system performance such as desalination yield, cooling output, coefficient of performance, gained output ratio, energy utilization factor are analysed for various ambient temperature and relative humidity. The maximum desalination yield and cooling output are 7.35 LPH and 1.89 kW respectively. The highest system coefficient of performance, gained output ratio and energy utilization factor are 2.16, 6.11 and 8.27 respectively at ambient temperature of 20 °C and 30% RH. The annual average desalination and cooling output are 25.884 m3/year and 4.26 MWh/year respectively. The exergy efficiency of the proposed system is 39.34%. The unit cost of desalination is estimated to be $0.0096/L. © 2020

Journal of Cleaner Production

Performance analysis of a novel augmented desalination and cooling system using modified vapor compression refrigeration integrated with humidification-dehumidification desalination

Applied Solar Energy

Performance evaluation of photovoltaic/thermal–HDH desalination system

Humidification–dehumidification (HDH) desalination is a simple technique to produce desalinated water from saline water. Dehumidifier is a key component in the HDH system, which influences the desalination yield. In the current work, a three-dimensional multiphase numerical simulation study is carried out on third dehumidifier alone to evaluate its performance using computational fluid dynamics (CFD) code. The simulation result is validated with experimental readings, and it is found that there exists a very close agreement between the predicted and the experimental readings. The key parameters influencing the dehumidifier performance are chilled water temperature, humid air temperature, and volume fraction. Experiments are carried out on the combined two stage HDH plant at different hot water temperature and flow rates. A detailed study of dehumidification process is carried out using ansys cfx 15.0 tool by solving the governing equations, namely, mass, momentum, and energy, with turbulence modeled through shear stress transport (SST) k–ω model of closure. Multiphase is solved using a free-surface multiphase model. The measured average cooled air temperature and relative humidity (RH) at the exit of third dehumidifier are 21 °C and 67%. The desalinated water produced at a hot water flow of 100 LPH is found as 2205 ml/h from the experiments. The CFD results are deviated by 0.41%, 6.45%, and −0.70% with that of experimental results at the dehumidifier for air temperature, velocity, and chilled water temperature, respectively.

Journal of Thermal Science and Engineering Applications

Experimental and Computational Fluid Dynamics Studies on Dehumidifier in a Combined Cooling and Desalination Plant

Humidifier is an important component in air humidification-dehumidification desalination plant for fresh water production. Liquid to air flow rate ratio is optimization is reported for an industrial cooling towers but for an air humidifier it is not addressed. The current work is focused on the design and analysis of an air humidifier for solar desalination plant to maximize the yield with better humidification, using finite difference method (FDM). The outlet conditions of air from the humidifier are theoretically predicted by FDM with the given inlet conditions, which will be further used in the design calculation of the humidifier. Hot water to air flow rate ratio and inlet hot water temperature are identified as key operating parameters to evaluate the humidifier performance. The maximum and optimal values of mass flow rate ratio of water to air are found to be 2.15 and 1.5 respectively using packing function and Merkel Integral. The height of humidifier is constrained to 1.5 m and the diameter of the humidifier is found as 0.28m. The performance of humidifier and outlet conditions of air are simulated using FDM and compared with experimental results. The obtained results are within an agreeable range of deviation. © 2017 Published under licence by IOP Publishing Ltd.

Fulltext

IOP Conference Series: Materials Science and Engineering

Design and development of an air humidifier using finite difference method for a solar desalination plant

Humidification–dehumidification (HDH) desalination works based on a water cycle principle and involves air humidification and condensation (dehumidification). The cooling of humid air with chilled water increases the desalination and results in cold air suitable for air conditioning process. The merits of the proposed HDH desalination and cooling are not analyzed and compared in the literature. Therefore, the performance results of HDH with normal water (current technology) and HDH with chilled water (proposed idea) are compared to highlight the merit of this cycle. The combined cycle for desalination and cooling has been solved thermodynamically with psychrometric properties. The results are validated with a laboratory experimental setup. The examined operational process conditions are hot water inlet temperature, efficiency of humidifier, and vapor absorption refrigerator's (VAR's) evaporator exit temperature. The focused results are desalination, cooling and energy utilization factor (EUF). The comparative study recommends the use of chilled water in the final stage. The two stage desalination with dehumidification by normal water in the first stage and chilled water in combined two stages improves the cycle EUF from 0.18 to 0.33. Out of 300 W of cooling generation, 100 W is used for dehumidification and the remaining 200 W is available for air conditioning process at 15 N⋅m3 h−1 of air. © 2017 Elsevier Ltd and IIR

International Journal of Refrigeration

Augmented desalination with cooling integration

A simple cooling cogeneration has been developed by coupling a Kalina cycle system (KCS) with a vapor absorption refrigeration (VAR) system. The working fluid used in this theoretical thermodynamic evaluation is ammonia water mixture. A low temperature heat recovery (150 °C–200 °C) from engine exhaust gas, solar collectors, or similar can be used to operate the plant. A controlling facility is provided to set the required amount of power or cooling to meet the variable demand. In this proposed plant, the liquid refrigerant absorbs more amount of heat from evaporator surroundings with a flow control located in between power and cooling cycles. The extra included components are condenser, heat exchanger and throttling device over KCS plant. Due to possibility of more cooling, it offers high energy utilization factor (EUF). The coupled plant characteristics are studied with changes in mass split ratio, separator vapor fraction, separator temperature, and turbine concentration to develop efficient working conditions. The power mass split ratio is varied from 80% to 100% to run the coupled plant at nearly full load conditions. The separator vapor fraction and temperature are optimized at 45% and 150 °C, respectively. It is recommended to maintain the turbine concentration above 0.85 for optimum power and cooling. The maximum cycle EUF and plant EUF are 0.15 and 0.06, respectively, at 80% power mass split ratio. The specific power and specific cooling at these conditions are 62 kW/kg and 72 kW/kg, respectively.

Journal	Data powered by TypesetDesalination
Publisher	Data powered by TypesetElsevier BV
ISSN	0011-9164
Open Access	No