The pressure drop of refrigerant R-134a flow boiling inside a horizontal tube has been investigated experimentally. The test set-up which was used in this investigation is a well instrumented vapor compression refrigeration system. These instruments are thermocouples, flow meter, pressure gauges and the pressure drop measuring apparatus. This system consisted of three electrically heated evapor...

The potential benefits of optimal service scheduling for cleaning heat exchangers based on minimizing operating costs are explored. A demonstration is performed on a simulated 20 ton air-to-air vapor compression air conditioner. The costs of regular service schedules (indicative of current practice), minimal schedules needed to maintain comfort, and the optimal schedules are compared. Generally...

Poverty, drug resistance and other factors including increasing difficulty in the control of mosquitoes (the vector of the causative organism of malaria), have led to a growing interest in phytochemical research. The antioxidant activity of Newbouldia laevis stem bark was investigated. Air dried stem bark of N. laevis was powdered and extracted with 95 % v/v methanol by maceration, and the extr...

Potential improvements of the Coefficient of Performance (COP) were investigated for R-407C at cooling and heating conditions of a residential heat pump. The study used CYCLE-11, a semi-theoretical vapor-compression cycle model, which was upgraded to simulate cross-flow, counter-flow, and parallel-flow evaporator and condenser with no restrictions on specifying superheated vapor and subcooled l...

A heat pump system requires proper refrigerant charge amount. Once refrigerant is charged into a heat pump system, its charge amount is fixed. For this reason, prediction of optimal refrigerant charge amount is very important in order to yield best performance. Too low charge amount degrades capacity of heat pump. On the other hand, excessive charge amount decreases coefficient of performance (...

Small amounts of useful power may be generated in polar or subpolar regions during the winter period by placing a heat engine between a large body of water (near PC), acting as a heat source, and the atmosphere (near -25OC), acting as a heat sink. The scheme consists of a fuelless modular system operating on the Carnot cycle. Power is extracted by a reciprocating vapour engine drawing saturated...

In this study an analytical model for open loop pulsating heat pipes (PHPs) is presented. The model predicts the effect of different parameters such as evaporator temperature, length of evaporator, filling ratio, number of turn and tube diameter on PHP's performance. The governing equations in two phase flow including mass, momentum and energy equations are solved for both one dimensional liqu...

This paper presents a mathematical model of heat pump exchangers and their thermal interaction with fan for an air dryer. The calculation algorithm developed the finned is based on ε-NTU method, allowing determination side refrigerant transfer coefficients, evaporator condenser capacity parameters at dehumidifier outlet known exchanger geometries, initial mass flow rate. was verified industrial...

Abstract Solar-powered desalination is an effective means to address the global freshwater shortage and combat water pollution. However, light absorption capacity, thermal insulation performance, transmission efficiency of most current solar evaporators cannot be effectively combined, resulting in a relatively low utilization rate energy. In this study, double-layer evaporator was reported by u...