Stephen Molivadas

US Patent:

6866092, Mar 15, 2005

Filed:

Aug 26, 1993

Appl. No.:

08/112204

Inventors:

Stephen Molivadas - Chevy Chase MD, US

International Classification:

F01P003/22
F28D015/00
F28F027/00

US Classification:

16510421, 123 4121, 123 412, 123 4125, 123 4126, 165 47, 16510427, 16510432, 165272

Abstract:

Various techniques are disclosed for improving airtight two-phase heat-transfer systems employing a fluid to transfer heat from a heat source to a heat sink while circulating around a fluid circuit, the maximum temperature of the heat sink not exceeding the maximum temperature of the heat source. The properties of those improved systems include (a) maintaining, while the systems are inactive, their internal pressure at a pressure above the saturated-vapor pressure of their heat-transfer fluid; and (b) cooling their internal evaporator surfaces with liquid jets. FIG. illustrates the particular case where a heat-transfer system of the invention is used to cool a piston engine () by rejecting, with a condenser (), heat to the ambient air; and where the system includes a heat-transfer fluid pump () and means () for achieving the former property.

US Patent:

53336771, Aug 2, 1994

Filed:

Aug 30, 1989

Appl. No.:

7/400738

Inventors:

Stephen Molivadas - Chevy Chase MD

International Classification:

F28D 1502
F28F 2700

US Classification:

165 32

Abstract:

Various techniques are disclosed for improving systems that include an evacuated, and in essence hermetically-sealed, fluid circuit containing a heat-transfer fluid which--while circulating, usually with the assistance of a pump, around the fluid circuit--absorbs heat, primarily by evaporation, from a heat source and releases the absorbed heat, primarily by condensation, to a heat sink; the maximum temperature of the heat sink being, at a given instant in time, lower than the maximum temperature of the heat source at that instant in time. The various techniques disclosed always furnish the fluid circuit with a property named `self-regulation`; and, where applicable, with one or more properties named `overpressure protection`, `freeze protection`, `heat-absorption control`, `heat-release control`, and `heat-source control`. Self-regulation ensures, by controlling heat-transfer flow around the fluid circuit, that the fluid circuit transfers heat efficiently over a preselected range of operating conditions comprising a preselected range of evaporation rates which includes at least two evaporation rates differing significantly from each other.

US Patent:

42112079, Jul 8, 1980

Filed:

Apr 2, 1974

Appl. No.:

5/457271

Inventors:

Stephen Molivadas - Washington DC

International Classification:

F24J 302

US Classification:

126433

Abstract:

A combined heating and cooling system includes a solar collector and evaporator for absorbing heat from solar radiation and/or the ambient air and for using the absorbed heat to evaporate a binary-phase, liquid-vapor working fluid. In the heating mode, whenever the temperature of the working fluid inside the evaporator of the solar collector is sufficiently higher than that of the medium to be heated, the working fluid follows a cycle similar to the Rankine cycle in which the heat engine is eliminated. Whenever the temperature of the working fluid inside the evaporator is no longer high enough for heat to be transferred unassisted to the medium to be heated, the working fluid is made to follow a heat-pump cycle. Finally, whenever the temperature of the working fluid in the evaporator falls below the temperature of the surrounding air, the evaporator is exposed to the ambient air and the system runs as an air-source heat pump. In the cooling mode, the system is run as a vapor-compression refrigeration cycle in which the compressor is selectively powered by the use of a solar-assisted Rankine power cycle.

US Patent:

43400302, Jul 20, 1982

Filed:

May 5, 1978

Appl. No.:

5/902950

Inventors:

Stephen Molivadas - Washington DC

International Classification:

F24J 302

US Classification:

126421

Abstract:

Various systems are disclosed for absorbing radiant heat, especially solar heat, by evaporating a refrigerant, and for releasing the heat thus absorbed to a medium to be heated, by condensing the evaporated portion of the refrigerant. The refrigerant fluid loop includes (1) an evaporator, or solar collector, including passageways where at least a portion of the refrigerant is vaporized, (2) a separator which may be a part of or a separate component from the evaporator, that divides the vapor portion and the liquid portion of the refrigerant exiting the evaporator passageways, (3) a condenser for condensing the vapor portion of the refrigerant and transferring the latent heat released to a medium to be heated, and (4) a condensate pump to return the liquid refrigerant from the separator and condenser to the evaporator. Systems are also disclosed for returning the liquid refrigerant to the evaporator by gravity thus eliminating the need for a condensate pump. Controls and component arrangements are shown for maintaining the temperature of evaporation of the refrigerant automatically insofar as practical just above that of the medium to be heated, independently of changes in the temperature of the medium, the temperatures of the system's surroundings, and the intensity of radiation intercepted by the system.

US Patent:

43589294, Nov 16, 1982

Filed:

Apr 28, 1980

Appl. No.:

6/144275

Inventors:

Stephen Molivadas - Washington DC

International Classification:

F03G 702

US Classification:

606418

Abstract:

Various control methods and means are disclosed for varying the temperature of vaporization of a solar-powered system so that the instantaneous power delivered by the heat engine of this system, or by a device driven by this engine, is a maximum for given conditions external to the power system, or to the power system and the driven device, respectively, while ensuring that dry saturated vapor, or vapor with a preselected amount of superheat is supplied to the heat engine. The power system uses a Rankine power cycle whose working fluid is either vaporized in the absorber of a solar collector, or in a heat exchanger by a separate fluid which absorbs heat by flowing through the solar collector absorber. Also, various methods and means are disclosed for controlling the foregoing separate heat-transfer fluid so that it absorbs sensible and latent heat in the absorber of the solar collector in essentially the same ratio as the power-cycle working fluid absorbs sensible and latent heat from this heat-transfer fluid.