Oceanic Thermal Energy Conversions Group Members: Brooks Collins Kirby Little Chris Petys Craig Testa

Background Information OTEC system is based on the Rankine Cycle OTEC system is based on the Rankine Cycle Uses the vertical temperature gradient in the ocean as a heat sink/source Uses the vertical temperature gradient in the ocean as a heat sink/source Mainly used in equatorial waters where temperature gradient is greatest Mainly used in equatorial waters where temperature gradient is greatest

Closed Rankine Cycle Overview 1-2 Power in to pressurize liquid to higher pressure 1-2 Power in to pressurize liquid to higher pressure 2-3 Heat addition to evaporate ammonia 2-3 Heat addition to evaporate ammonia 3-4 Work produced from expansion through turbine 3-4 Work produced from expansion through turbine 4-1 Heat extraction to condense the ammonia before pump 4-1 Heat extraction to condense the ammonia before pump

Closed Rankine Cycle Calculations

Pros of OTEC Extremely benign impact on environment Extremely benign impact on environment No dependency on oil No dependency on oil Minimal maintenance costs compared to conventional power production plants Minimal maintenance costs compared to conventional power production plants Open cycle OTEC systems can produce desalinated water which is very important in third-world countries 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 Low thermal efficiency due to small temperature gradient between heat sink and source OTEC technology is only ideally suitable in equatorial waters OTEC technology is only ideally suitable in equatorial waters Only moderate power outputs are available Only moderate power outputs are available Currently this technology is not as monetarily feasible as conventional power production plants 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. 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 of OTEC power production. 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 of OTEC power production.

Specifications Produce 100 Watts of power Produce 100 Watts of power Be smaller than 8 ft. wide, 6 ft. tall, and 2 ft. deep. Be smaller than 8 ft. wide, 6 ft. tall, and 2 ft. deep. Final product must be easily portable. 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. 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 start and stop operation using simple mechanical or electrical devices Must not endanger the operator or anyone viewing the OTEC presentation 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 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. Many moderately sized Geothermal energy cycles use large commercially available AC units. Objective is to make the compressor function as a turbine/generator Objective is to make the compressor function as a turbine/generator Add an auxiliary pump to circulate and pressurize the working fluid throughout the cycle Add an auxiliary pump to circulate and pressurize the working fluid throughout the cycle Very little modification is necessary to convert heat pumps and AC units into power producing units Very little modification is necessary to convert heat pumps and AC units into power producing units

Future Calendar

Future Design Plans Research Heat Pump Conversion Research Heat Pump Conversion Find pump that fits mass flow rate and pressure specifications 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 Determine whether shell and tube or plate and frame heat exchanger will be more efficient Select piping sizes based on calculations Select piping sizes based on calculations Find optimal size of heat exchangers for effective heat transfer between the ammonia and the heat sink/sources Find optimal size of heat exchangers for effective heat transfer between the ammonia and the heat sink/sources