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Experimental simulations of a sustainable desalination process have been carried out using a pilot unit. Experiments were conducted at analogous conditions to simplify design evaluation but with different values of the controlling variables to enhance analysis and modeling. The proposed desalination process, which, employs solar heating and passive vacuum generation, has been theoretically simulated in earlier work. It entails flowing seawater through a condenser to preheat it and then through a heater before flashing it in a vacuumed evaporator connected to the condenser where the flashed hot vapor is condensed by the incoming cold seawater forming fresh water All experiments were run for the same period of time starting at the same initial vacuum. Experiments were carried out at different seawater flow rates and different flash temperatures. In addition, each experiment was duplicated three times to validate its outcome. Flashing seawater at higher temperatures increases vaporization and fresh water production rate. In addition, the accumulating noncondensable gases that are slowly eroding the vacuum will decrease the overall vaporization with time, which reduces the production rate of fresh water. [DOI: 10.1115/1.4002557] Keywords: solar flash desalination

A new desalination scheme has been proposed. The system consists of a saline water tank, a concentrated brine tank, and a fresh water tank placed on ground level plus an evaporator and a condenser located several meters above the ground. The evaporator-condenser assembly, or flash chamber, is initially filled with saline water that later drops by gravity, creating a vacuum above the water surface in the unit without a vacuum pump. The vacuum is maintained by the internal hydrostatic pressure balanced by the atmospheric pressure. The ground tanks are open to the atmosphere, while the flash chamber is insulated and sealed to retain both heat and vacuum. A theoretical simulation of the proposed model was carried out using a detailed model built by employing the fundamental physical and thermodynamic relationships to describe the process and was complimented by reliable empirical correlations to estimate the physical properties of the involved species and the operational parameters of the proposed system. The simulation results show that running the system at higher flash temperatures with a fixed flash chamber size will result in faster vacuum erosion leading to less overall evaporation. [DOI: 10.1115/1.3142724] Keywords: desalination, flash desalination, solar desalination

1 Introduction With the proliferation of portable computing platforms and small wireless devices, ad hoc wireless networks have received more and more attention as a means of data communication among […], Power-saving is a critical issue for all kinds of portable devices. The power-saving mode of IEEE 802.11 is designed for a single-hop (or fully connected) ad hoc network and is not applicable for multi-hop ad hoc networks. In this paper, we propose an asynchronous power-saving protocol for mobile ad hoc networks (MANETs) with unpredictable mobility and multi-hop communication. Neighbors that wish to communicate estimate the relative phase difference between their sleep/awake cycles. A station uses this phase information for transmitting the pending traffic. Stations can also increase their awake period for transmitting the data and to reduce latency for delay sensitive flows. Simulation studies indicate that the proposed asynchronous protocol is quite effective under various traffic characteristics and loads; energy saving can be as high as 70%, while the packet delivery ratio is comparable to networks without power management. Key words: 802.11, ad-hoc networks, clock synchronization, scalability

New design of a falling film absorber that could considerably reduce the absorber size without penalizing the vapor and coolant side pressure drops is presented. The results show that the proposed design is more compact and efficient than the horizontal tube-type falling film absorber.