This paper presents the experimental as well as the simulated performance studies on the transcritical CO2 heat pumps for simultaneous water cooling and heating; effects of water mass flow rates and water inlet temperatures of both evaporator and gas cooler on the cooling and heating capacities, system COP and water outlets temperatures are investigated. Study shows that both the water mass flo...

Multi-evaporator vapor compression systems (ME-VCS) provide cooling to multiple zones. The thermodynamic conditions in these zones are independent: the heat loads often differ, and the occupants of these spaces often have different desired room temperatures. Therefore, in order to regulate each zone to its desired setpoint temperature, the amount of thermal energy removed by each evaporator mus...

Fred Keller Split Systems Director The National Appliance Energy Conservation Act has established a minimum efficiency of 10 SEER for residential split system air conditioners and heat pumps. Approximately 50% of residential split system air conditioners are sold as replacements for units having much lower SEER levels, typically 5-9 Btu/W·h. This investigation assessed the detrimental affects t...

Title of Document: HIGH-PERFORMANCE TUBULAR EVAPORATOR UTILIZING HIGH ASPECT RATIO MANIFOLD MICROCHANNELS Vibhash Chandra Jha, Doctor of Philosophy, 2012 Directed By: Michael Ohadi, Professor Department of Mechanical Engineering Heat recovery using absorption chillers has not been economical for small scale applications due to high capital requirements and heavy weight/volume as deterring facto...

A heat pump system is constructed tO evaluate the performance and the heat transfer characteristics. Mixtures of R22/Rl42b are adopted in the heat pump. The heat transfer in the evaporator and the overall perfomance arc measured and analyzed in terms of the compositions and the flow rate of the refrigerants. The evaporator consists of counter~currem concentric circular tubes. Possibility of cap...

Loop heat pipe evaporators operating under steady state conditions were numerically investigated to describe evaporator characteristics and evaluate evaporator performance. Numerical solutions were obtained for conjugate flow and heat transfer in primary evaporator components. Two geometrical configurations used for cylindrical LHP evaporators, a non-bayonet evaporator and a bayonet evaporator,...

Residential air conditioning is responsible for a substantial amount of peak electrical demand and energy consumption throughout most of the United States. Coil fouling, the deposition of indoor dusts and other particulate matter on evaporator heat exchangers, increases system pressure drop and, correspondingly, decreases system air flow and air conditioner performance. In this paper, we apply ...

Continuous capacity modulation, for example by varying compressor speed, is only one alternative to conventional cycling of vapor compression systems. Cycling the compressor at higher frequencies (~0.01–0.1 Hz) than conventional systems (~0.001 Hz) offers a potentially simpler and less costly alternative. Experiments were conducted to quantify effects of steady vs. pulsed flow on the performanc...

This paper presents the benefits in capacity and performance of a hybrid control of expansion valves for two 5-ton (17.6 kW) domestic heat pumps (HPs) based on experimental results. The hybrid control, as proposed by Kim et al. (2008a), employs a primary expansion valve that provides most of the pressure drop, while small secondary/balancing valves in the distributor lines to the circuits of th...