Oceanic Thermal Energy Conversions Group Members: Brooks Collins Kirby Little Chris Petys Craig Testa
Background Information • OTEC system is based on the Rankine Cycle • Uses the vertical temperature gradient in the ocean as a heat sink/source • Mainly used in equatorial waters where temperature gradient is greatest
Closed Rankine Cycle Overview • 1-2 Power in to pressurize liquid to higher pressure • 2-3 Heat addition to evaporate ammonia • 3-4 Work produced from expansion through turbine • 4-1 Heat extraction to condense the ammonia before pump
Pros of OTEC • Extremely benign impact on environment • No dependency on oil • Minimal maintenance costs compared to conventional power production plants • Government cannot tax OTEC plants that are off-shore. • Provide air conditioning to buildings within the OTEC plant • Open cycle OTEC systems can produce desalinated water which is very important in third-world countries
Cons of OTEC • Low thermal efficiency due to small temperature gradient between heat sink and source • Available only in equatorial waters • Only moderate power outputs are available • Currently this technology is not as monetarily feasible as conventional power production plants • The manufacturing and installation of the extremely long cold water pipes is extremely time consuming and costly.
Problem Statement • To create and design an operating Oceanic Thermal Energy Conversion model that employs a closed Rankine Cycle that utilizes ammonia as the working fluid to illustrate the viability.
Specifications • Produce 100 Watts of power • Be smaller than 8 ft. wide, 6 ft. tall, and 2 ft. deep. • Final product must be easily portable. • OTEC model must be aesthetically pleasing and allow viewers to easily understand and view the inner-workings of the Rankine Cycle utilized by OTEC systems. • Must start and stop operation using simple mechanical or electrical devices • Must not endanger the operator or anyone viewing the OTEC presentation
Heat Pump Conversion • One possible design idea is to convert a heat pump into a power producing Rankine Cycle • Many moderately sized Geothermal energy cycles use large commercially available AC units. • Objective is to make the compressor function as a turbine/generator • Add an auxiliary pump to circulate the working fluid throughout the cycle • Very little modification is necessary to convert heat pumps and AC units into power producing units
Research Heat Pump Conversion Find pump that fits mass flow rate and pressure specifications Determine whether shell and tube or plate and frame heat exchanger will be more efficient Select piping sizes based on calculations Find optimal size of heat exchangers for effective heat transfer between the ammonia and the heat sink/sources Future Design Plans