In areas with very hot weather conditions (50 to 60℃), the temperature and pressure of the airconditioning condenser are increased considerably. This causes a decrease in the cooling capacity of the cycle and also causes an increase in the power consumption due to increased pressure ratio. In this work, an experimental and theoretical investigation has been done to improve the evaporator outlet fluid temperature through enhancing condenser performance. For this purpose, several modifications on the refrigeration system have been developed and tested to solve this hot weather problem. The air-side modifications include adding Spray Water above condenser (SW), wet Pad before condenser (Pad), and water Vapor Nozzle in the condenser air flow (VN). The refrigerant-side modification includes adding a pair of Heat Exchangers (HE) for exchanging heat between condenser exit and evaporator exit by using water-antifreeze mixture as a working fluid. A Water-Refrigerant(W-R) evaporator has been designed, manufactured, and compared with original Air-Refrigerant(A-R) evaporator performance. All air and refrigerant-side modifications have been investigated using both types of evaporators. The results indicate that the (SW) modification for enhancing condenser performance is the best method for COP improvement. The COP of (SW) system is found to increase at rate of (44.5 %) and (102.1%) as compared to system without modifications for (A-R) and (W-R) evaporators respectively. The outlet cooling temperature from evaporator has been found to reduce by about (30.3%) for (A-R) evaporator and (23.6%) for (W-R) evaporator. However, (HE+Pad) modification has been found as the best method for improving air side Nusselt number of condenser with an increase of about (4.7) times that of system without modifications. Ten new Nusselt number correlations have been predicted for each type of modifications under investigation by using both Engineering Equation Solver (EES) software and the experimental data. Cost-Benefit analysis in terms of life cycle cost, net present value, cost-benefit ratio, and payback period have been conducted. From the analysis, it can be concluded that using (SW) system will save a significant amount of energy with a payback period of less than five years.
In the manufacturing field of industrial firms, some materials are hard to cut and do not meet the mechanical operation requirements in conventional and unconventional machining methods due to their high mechanical properties which poorer their machinability. The need is ongoing and growing to these materials in important industries, therefore hot machining is considered one of the most advanced methods of machining which help to solve the problem of these materials. This process involves heating the work piece at elevated temperature during or before machining on conventional cutting machine by using various external heating techniques, which soften it and becomes more ductile and this leads to improve the machinability. This paper displays a review on hot machining process and presents its effectiveness for the industrial firm in machining hard-to cut-materials which reflect on cost and productivity in relation to other aspects of machining. The review paper presents a survey on various researches which indicates the effect of variation process parameters in hot machining.
In hot weather countries, the temperature and pressure of the airconditioning system are increased considerably. This causes a decrease in the cooling capacity of the cycle and also causes an increase in the power consumption. In this work, an experimental and theoretical investigation has been done to improve the evaporator outlet fluid temperature. Engineering Equation Solver (EES) software has been used to analyze the performance of the experimental data. For this purpose, several ranges of evaporator water flow rate are considered tested. The amount of water flow rate is varied with respect to the evaporator load. The results indicate that the increase of water flow rate (160 to 190) L/h causes increase of COP by (11.1 %). The outlet cooling temperature from evaporator has been found to reduce by about (11.3%). However, (170 L/h) flow rate of water has been found as the best rate for improving evaporator temperature.
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